Basics: Headspace

Setting Proper Headpace on Resized Cases
by Germán A. Salazar
Setting the headspace on a resized case is important to ensure reliable functioning of the rifle, avoid damage to the rifle, maximize case life and achieve consistent accuracy. The objective of this article is to show you a method of setting up a full length resizing die that allows you to quickly adjust its setting to achieve the desired amount of shoulder set-back (headspace) for a number of rifles chambered for the same cartridge or for different lots of brass.

"Headspace" in the context of the rifle chambered for a rimless cartridge is actually the distance from the bolt face to the point in the chamber that is halfway up the shoulder. In the reloading context we often use the term to indicate how much clearance have we built into the brass case as compared to that distance. Simply stated, if the headspace measurement on a resized piece of brass is 0.002" less than the chamber headspace of the rifle in which it was fired, we often say the brass has 0.002" headspace. That's not a technically correct use of the term, but it will do for most reloading purposes.

Brass is a fairly "live" metal, it conforms to the chamber dimensions under the pressure of firing and as the pressure drops, it springs back towards its original dimensions, although not all the way back - that's why we resize cases. If it didn't spring back at all, extraction would be very difficult; you get an idea of that with an over-pressure load where the brass, in fact, does not spring back enough to allow easy extraction.  Brass fired at normal pressures springs back in both length and diameter, both need to be addressed in resizing in order to make the brass hold a bullet again and go into the chamber properly.

Brass that is only neck sized will hold a bullet, but will chamber hard and with each firing will chamber harder yet. The reason for this is that is has essentially no headspace, just a little from the spring-back, and the radial dimensions also have insufficient clearance. Hard chambering tends to wipe the lube off of the locking lugs, leading to galling of the lugs in a relatively short time. In addition to damaging the rifle, hard chambering and extraction are hardly what a competitor needs in the middle of a match.

Let's look at a method of full length sizing that allows you to control the headspace of your brass and to easily adjust the die for proper headspace from one rifle to another or even one lot of brass to another. Yes, different lots of brass might require a slightly different setting of the die to achieve the same headspace because the metallurgy of the brass may be slightly different. The same can happen as the brass hardens a bit after many firings.

First, you'll need a method of measuring the headspace of the fired brass and the resized brass. Hornady makes a tool for this and there are others as well such as Wilson and Forster. I usually use a piece of barrel steel into which the shoulder area of the appropriate chamber has been cut. Either way will do a perfectly good job. The gauges made by Mo DeFina are also very useful for this process. Whichever method you use, the objective is the same, we want to measure the headspace dimension of the brass before and after resizing to make sure that we've created the headspace clearance we're after.

Second, loosen the lock ring on the die and move it up on the die. Get a #17 O-ring (7/8" x 1/16") from you local Ace Hardware and slide it over the die so that it will go between the lock ring and the press. Run the ram in the press all the way up and screw down the die until it makes contact. Now, lower the ram and screw the die in 30 degrees more (make a mark at 6:00 and turn it to 7:00). now, raise the ram again and you will feel it bump, but it will still go all the way. Next, with the ram still bearing against the die, lower the lock ring and once it begins to compress the O-ring keep turning until it feels slightly firm, that should be about 1/8 of a turn. Lock the lock ring, lower the ram and with a Sharpie type marker make an index mark on the press. Erase any index mark you may have made on the lock ring from the earlier 30 degree setting. At this point there should be a mark on the press and none on the die.

If the shellholder doesn't come into solid contact with the die solidly enough to make it cam over (that's the bump feeling) then it won't set the shoulder back. That was the first part of what we did. Second, by using the O-ring method, what we've done is created a setup in which the die will slightly float under pressure from the ram and this keeps things more centered. Thirdly, the O-Ring setup allows you to tweak the die up and down a tiny bit as needed to really set the amount of shoulder setback properly for your rifle and brass. Resized brass headspace should be between 0.001" to 0.002" less than the headspace of the fired case.

Using and Adjusting the O-ring Die
Wih the die now set up in the press, take a few fired cases and deprime them - not by running them into the die, use a manual decapping stem or a decapping die. Decapping prior to this initial measurement is important because any slight primer cratering or protrusion will affect our readings. Using your gauge, measure each case for headspace and make a note. During setup, I'll write it directly onto the case with the Sharpie. With the die at the initial setting, size two of the cases and check the headspace again. Ideally the headspace will be between 0.001" and 0.002" less than the fired cases - this is for a bolt action rifle, for a semi-auto use 0.002" to 0.003" headspace. The consistency of your case lube application will affect the consistency of the headspace dimension.

Adjust the die in or out as appropriate to get to the desired dimension, check two cases per setting to make sure of the setting. Once you have the setting where you want it, make a Sharpie mark on the die's lock ring to index to the mark on the press. The setting will repeat very well from session to session. You'll find that older brass or brass from a different rifle will call for a slight change in the setting, but you'll have a good place to start. I check headspace each time I reload brass, while it may seem like a lot of work, it's really just a couple of minutes of effort - well worthwhile for enhanced reliability and brass life.

Here are a few pictures to clarify things.


1. The die with the O-ring, self-explanatory.


2. The die on the press with the index mark visible. The second index mark is for another rifle with a shorter headspace.



3. A homemade (by a friend) headspace gauge that is simply a piece of steel with the exact angle of the shoulder cut into it and a hole big enough for the neck to pass through.  The same thing can be done nicely with a cut-off piece of the barrel and the chambering reamer when your new barrel is installed.  Wilson and Forster also make useful gauges for this purpose.



4. The gauge with a true chambering headspage gauge in it. You'll see the pointer on the caliper rests on zero. There's no critical thickness for the gauge, it could be anything since what you'll do is simply compare fired brass to sized brass and check the difference. Since it looks nice with the pointer at 0 my friend ground the gauge to the thickness that yielded that setting. Rotating the dial on the calipers, or setting digital calipers to zero would achieve the same result. You don't need the chambering headspace gauge for the die setup, I just used it to show "true zero". All that really matters is the difference between the fired cases and the sized cases.



5. The gauge with a piece of sized brass in it. The rifle it was fired in gives brass that reads 0.004" when fired, so I try to size it to read between 0.002" and 0.003" (set it back 1 to 2 thousandths). This piece has already been sized and will slip in and out of the chamber with no resistance and is not overworked as it would be if I had taken it all the way back to 0. It will last longer this way.  When using this type of gauge, be sure to remove the primer before taking the measurement.  Obviously, if you do that in the sizing die you won't get the reading you needed, so use a simple decapping die or a primer punch such as those sold by Wilson or Lee.





Headspace measuring tool from Mo's Competitor Supplies.  The case goes inside the gauge and the cap screws on, you read the amount over or under "0" directly on the cap against an index mark on the gauge body.  MCS Inc., 34 Delmar Dr., Brookfield, Connecticut 06804 ph:203/775-1013


For more information on this and related topics, see Measuring the Case.

 Update - October 28, 2009.
I've just become aware of a very nice looking tool to measure headspace.  While I haven't tried it, it looks to be well thought out and nicely made.  If anyone tries it, I'd like to hear about it.  The tool is made by Innovative Technologies.



Primers: Misfires

Misfires
by Germán A. Salazar

NEW 09-06-09, see end for update.

The topic of misfires is a frequent one which I try to address in the forums. The questions are frequently posted on various forums in relation to the Russian primers (KVB, PMC, Wolf) as they have a harder cup than most US made primers and this is a factor in the misfire situation. I'll start this post with a recent question posted on http://www.6mmbr.com/ and my answer. I hope to add more to it over the next few days.

Question posted by Ridgeway:
I have 5k of the new Wolf SRM primers with the gold cups. I used almost 100 primers and I had a missfire! I never had an issue with CCI, Fed or Remington since I've been reloading in '90. I even have primers from the early '80's that I use for fire forming that work! Anyone else have missfires with Wolf? I hope this is not a trend for 5k worth of primers!

There was not a problem with seating...I use a K&M priming tool. The cup definitely bottomed out. I'm on my 8th firing on a Dasher case...the primer pockets aren't as tight as they used to be and its easy to feel.I even re-cocked with the dud in the chamber and re-fired. Nothing. Did that like 3 times. Once I removed the round...the cup was a little distorted from being hit numerous times with the pin.

Answer 1 (German):
Ridgeway, have you installed a light firing pin in the rifle? Has the spring been checked lately?Either condition (light pin, worn spring) can lead to misfires. This is assuming that the primers are properly seated since you indicated that you are confident of that.

Reply 1 (Ridgeway):
German...the action is a new Panda with about 375 rounds on it. No modifications have been made to the bolt spring or pin. I re-cocked like 3-4 times and nothing happened other than smash and distort the primer. Is the spring in a Panda bolt on the light side?Primer seating...I can definetly feel them bottom. This is just one incident...not going to worry unless it happens again. Maybe its a fluke?

Answer 2 (German):
I don't know if the Panda firing pin and spring are lighter than "standard" which I define as a Remington 700. I'll see what I can dig up, Otteson's book The Bolt Action Rifle might have those specs. I'll check.

Let's take a look at some specs from: Otteson, The Bolt Action Rifle,
Vol. 1, pg. 138, Rem. 700 (short action, post 1968):
Lock Time: 2.6 ms
Firing pin fall (to impact): 0.213 in.
Impact velocity: 15.2 ft./sec.
Impact energy: 87.2 in.-oz.
Impulse: .96 oz. sec.

Unfortunately, Otteson didn't specify the weight of the firing pin on the 700. Impact energy and impulse, by the way are important to proper ignition, but often overlooked in the overemphasized quest for fast lock time. All modern rifles have darn good lock times and improvements are nearly meaningless - except as they reduce energy and impulse and thus reduce ignition reliability.

As we move on to the Panda, we run into a brick wall, because Otteson covered that action in his later book Benchrest Actions & Triggers, and the level of detail provided on the basic action functions is greatly reduced.

Lock Time: 2.7 ms
Firing pin fall (to impact): 0.24 in.

Beyond those scant figures, we are told: "The firing pin assembly follows a Remington pattern except for a smaller diameter striker tip, which allows better primer support." Indeed, the closeness of the figures indicates a great similarity in the underlying mechanism. Let's bear in mind however, that while the Remington probably hasn't changed in the 30+ years since the review, the Panda may have evolved a bit, so let's not assume these specifications necessarily remain valid for current production Pandas.

I don't have a Remington firing pin to weigh, other than the one in my 40X. If you want to take your Panda apart and weigh the firing pin with the cocking piece and separately weigh the spring (1/2 the weight of the spring should be considered in the weight of the striker) then I will do the same with the Remington.

While you have ruled out primer seating as an issue, for the benefit of others, I will say that primer seating is the primary area to examine in these situations and only after it has been determined that you are doing it correctly should your attention turn to the firing mechanism. The primer should bottom in the cup and then a slight additional forward movement, which gives a small degree of pre-compression to the pellet, should be felt. I have never been able to get this degree of "feel" from a press mounted priming tool. I use the Sinclair tool, but the K&M tool is equally good; the RCBS hand tool will do, although its heavy spring reduces feel to a certain degree.

One last thing - you asked if it might be a fluke, a bad primer or two in the lot. Generally speaking, no. Modern primer manufacture in the US and abroad and especially in the Murom plant where the Wolf primers are made, is held to such a close standard that the possibility of a bad primer is infinitesimal, the odds of more than one are essentially zero. When misfires are experienced, the primer is generally the last place to look for the cause. I'm not suggesting it is impossible to have a bad primer, simply that the probability of that is exceedingly low.

That the primer would not fire with repeated hits is normal. Once a primer has been struck, the pellet is complressed to a degree. If the impact energy and impulse were insufficient to ignite, there is not enough compression distance remaining in the primer (between the cup and anvil) to ensure ignition on a subsequent strike. In some cases it might, but it shouldn't be counted on.
UPDATE 09-06-09
It's a good thing we never stop learning - even if the lesson is delivered via a good helping of crow. I went to a match today and got 100% misfires with Russian primers in my .30-06, a first occurence. I stopped trying after 5 cases because I thought I knew what happened and it would be a 100% failure rate. When I got home and checked things out, I was right - a bad case of tolerance stack. Read on...
As some of you know, there is 0.010" manufacturing tolerance from the minimum to the maximum headspace length in a .30-06 chamber in accordance with SAAMI standards, so that is the acceptable range for a chamber. By measuring fired brass versus a "Go" gauge, I know that the chamber in this rifle is at 0.003" over minimum, OK, still good.
The new brass measured -0.002", so there's a built-in 0.005" clearance from case shoulder to chamber shoulder on the first firing of this brass (see the Headspacing article here if this concept isn't clear).
The new lot of Russian primers is a bit lower in height than the old ones.
The primer pockets on the new Winchester brass might be a bit deeper than the old brass. Whichever is the cause, the primers are noticeably deeper in the primer pocket than the old brass and primers.
I seated the bullets to jump 0.020", so there was no resistance to forward movement.
So.... with the 0.005" headspace, deep primers with hard cups and no resistance, I got misfires despite my heavy long-action Remington factory firing pin with a fresh spring. Man, that's sure some tasty crow.
I'll pull the bullets, reseat them to jam into the lands in order to press the case head against the bolt face and that should take care of it. On the next firing, with headspace reduced a few thousandths it should be no problem. We'll see...

History: Dad Farr and the Farr Trophy

George "Dad" Farr and the Farr Trophy

Service Rifle shooters at Camp Perry compete in two 1000 yard matches which are fired simultaneously with the Leech Cup and the Wimbledon Cup, they are the Porter Trophy and the Farr Trophy. The Porter is fired alongside the Leech Cup and the Farr alongside the Wimbledon Cup. The Farr Trophy has a very compelling history, below is the story of George "Dad" Farr as it appeared in the October, 1976 American Rifleman and also Dad Farr's obituary from the August, 1935 American Rifleman.

"Dad" Farr's 1921 Record Still Waits To Be Broken
by J.B. Roberts, Jr.

That high power shooter George R. Farr would establish a virtually unbreakable record at the 1921 National Matches seemed unlikely - especially to Farr himself. But what he did and the conditions under which he did it rank Farr among the most memorable of America's competitive shooters.
George Farr was by some accounts a lumberjack. In later years he worked as a gunsmith in Seattle, Washington. Called "Dad" by his fellow shooters, he was probably better known because he was the sort of man everyone liked than for his marksmanship. Personality aside, Dad Farr's shooting was worthy of all the admiration it won him.
The star of the 1921 matches was Marine Sergeant J.W. Adkins. Adkins had already won four major long-range events when he fired 75 consecutive bullseyes at 1000 yards and won the Wimbledon Cup. Adkins used a telescope-sighted M1903 Springfield rifle and commercial 180 gr. .30-06 Match ammunition to fire the third possible on the Wimbledon course in 30 years.
At 4:30 p.m., Sept. 4, 1921, as Adkins was finishing his record string, Dad Farr walked up to the firing line. He carried an M1903 rifle drawn from Ordnance supply that morning because his own rifle was not working, a homemade spotting scope, and 22 rounds of 1921 National Match ammunition. Farr's first sighter was a 3; his second a 5. Following the second sighter, Farr fired 20 bullseyes - the first time he had ever fired a 1000 yard possible. He then prepared to leave the line, for he had used all his ammunition. The range officer gave Farr two clips of ammunition, sent him back to the line, and spent the next hour looking for ammunition to keep him shooting. Between 4:30 when he began firing and 6:10 when darkness caused him to drop a shot into the 4 ring, Farr fired 70 consecutive record bullseyes.
Farr's feat was truly awe-inspiring. Firing with borrowed equipment, using metallic sights in the rapidly failing light, and at the age of 62 years, he came within five shots of beating Sgt. Adkins' score which was fired with a scope-sighted rifle. The service rifle record Farr set 55 years ago (now 88 years ago -GAS-) still stands. Because of the change in the target, it will probably never be broken.
To commemorate Dad's skill, competitors at the 1921 matches purchased the rifle he used from the government and presented it to him. They also instituted the Farr Trophy which has been awarded to the high service rifle shooter in the Wimbledon Cup Match for each year's competition since 1922.


The following obituary appeared in the August, 1935 issue of American Rifleman:
For George R. Farr, one of the Nation's most picturesque and inspiring riflemen, "cease firing" has sounded; and this grand old sportsman of Washington, after a life of 76 years of vigorous activity and worthy accomplishment, now rests tranquilly among the hills of his beloved Evergreen State. "Dad Farr," as he was affectionately known to his thousands of friends and acquaintances, was one of those outstanding characters among men. His cheerful and magnetic personality drew men to him, while his sound philosophy and exemplary leadership held their loyalty through the passing years.

Few men, through their marksmanship, have or ever will impress youth as he did at the age of 62, when in 1921 as a member of the Washington State Civilian Team he startled the shooting world by making a world's record of seventy-one consecutive bullseyes at 1000 yards in the classic Wimbledon Match at Camp Perry, and that with the Service rifle and its iron sights. Only the failing light from the sun below the horizon prevented an even higher score. As a result of that marvellous example of superb holding, aiming, and concentration the 2,000 riflemen assembled for the National Matches acclaimed Farr as a hero, and by voluntary subscription donated a massive silver bowl to be known as the George R. Farr Trophy and open to users of the Service rifle in future Wimbledon Matches.

Not only was Dad Farr a distinguished range shot, but his marvelous long-range shooting at game is a legend in the Pacific Northwest, and far exceeds the accomplishments of the popular riflemen of tradition. He gloried in long shots at mule deer and mountain goats among the rugged peaks of the Cascade Mountains; and as indicative of his sportsmanship, his aiming-point was always the neck, so that his shot if not a clean kill was an equally clean miss that enabled the quarry to escape uncrippled. The National Rifle Association has lost a distinguished life member, and the rifle fraternity an inspiring example of superior sportsmanship; but those of us who have hunted with him, and have been blessed with an intimate association, have lost a friend that can never be replaced.

You can see a picture of Dad Farr's rifle here: http://www.odcmp.com/NM/2003/2003NM_Bulletin_GunsDisplay.pdf

Related article here:
http://www.bobrohrer.com/sea_stories/end_of_an_era.pdf

Note: There is a discrepancy in the two articles, one indicating 70 bullseyes, the other 71. Whichever is correct, the feat remains as impressive today as it was in 1921. The 36" 5 ring was the whole black on the target; just seeing it at 1000 yards through the 1903's sights was a good feat, hitting it 70 or 71 times in a row in fading light was an accomplishment for the ages. -GAS-
I gathered the following data from the website of the US Naval Observatory,:
The following information is provided for Port Clinton, Ottawa County, Ohio (longitude W82.9, latitude N41.5):
Sunday 4 September 1921 Eastern Standard Time

Begin civil twilight 5:32 a.m.
Sunrise 6:00 a.m.
Sun transit 12:31 p.m.
Sunset 7:01 p.m.
End civil twilight 7:29 p.m.

Matches: Club Match, Mesa, Arizona

Late Summer Club Match - Mesa, Arizona
A Day Well Lived
by: Germán A. Salazar

This is not a match report, there are few if any scores in here. However, I hope that this gives the flavor of a typical Phoenix area club match to those of you who are thinking about coming out and for our friends overseas who only know our big matches like Camp Perry and the Spirit of America Match. This is a far more typical day in the life of a competitive shooter in the US and particularly in the Phoenix area. Our actual match reports are here.

The alarm clock goes off at 4:50 am, always too soon and now that summer is waning it's still dark at this hour. I hear the coffee maker gurgling and the scent of fresh Colombian coffee wafts into the room. Dress quickly and quietly, can't disturb the bride; 24 years and she still says I make too much noise in the mornings and she's right about that. It's a 65 mile drive from my house just outside the Valley of the Sun (sometimes the surface of the sun) down to the Rio Salado Sportsmans Club in Mesa so there's no time to waste. I pour a travel mug full of coffee and at 5:20 am I get into the little Ford Ranger which was packed last night with all the gear for the match and a few other goodies. Five minutes later I'm on the road, heading south into the Valley.



The Valley is not only surrounded by mountains, there are also a few outcroppings within it. I was born in the mountains and grew up there, at about 10,000 feet. We're not that high here but the peaks are a comforting sight and the soft mountain music on the radio the perfect accompaniment. However, as we get deeper into the Valley, the small town station crackles and fades so I switch to the local oldies station. They're playing the Beatle's 1964 concert at the Hollywood Bowl; it's been a long time since then.
In 1963, Mid Tompkins, then on the Air Force Rifle Team, won the bolt gun Highpower championship at Camp Perry with a .308; the first win with a cartridge other than the .30-06. Larry Moore won the Wimbledon Cup with a .30-06; that may be the only time that the old '06 was used to win that most prestigious of matches since 1935 when Ben Comfort won with the .300 H&H Magnum and started the magnum craze. Bob Jensen won the rapid fire warm-up match and got his picture in the American Rifleman. Bob would become one of the dominant .30 Caliber shooters of the 1960's, '70's and '80's and this was a first taste of success on the big stage. Another Phoenix shooter, Lou Roninger, won the '63 civilian service rifle championship and the Palma Individual Trophy. Lou left us for the happy hunting grounds about a year ago; he was a fine shooter, gunsmith and was instrumental in the organization of the 1970 ISU World Championships in Phoenix.
In 1964, people were eager to see if the .308 was for real or if Mid's win with it had been a fluke. No fluke, 1964 was a repeat of '63 with Mid once again winning the bolt gun championship with his .308 and the Leech Cup using a magnum. Although he won the Highpower championship with a .30-06 in 1958, Mid liked the short cartride more and brought a sea change to .30 Caliber shooting. The Beatles sang "Roll Over Beethoven" in Los Angeles while 2,500 miles away, the Highpower world was rolling over as the .30-06, king of the range for nearly 60 years was dethroned. Bob Dylan released The Times They Are a-Changin' in 1964, how right he was...

Time and miles fly by as I think about old days and soon enough I see the big PHOENIX sign on the mountain in Mesa that tells me I'm just about at the club. I don't know how many lost pilots that sign has guided to Phoenix, but it's a good wake-up call for match shooters arriving at Rio Salado. I'll be shooting the .30-06 today, I know that Doug Frerichs and Phil Hayes will be shooting the .308; don't know what Jim Cobb will shoot. Tough competition, as always down here. Hard holding Southwestern shooters aren't just something from cowboy movies or old days at Camp Perry, they're reality here and now - there are no easy wins here and it should be a close match.

6:35 am, I drive into the pits and find Mike Toliver, our match director already at work. He's been out during the week with a welder doing repairs and upgrades on the target carriers. A few of us get to work putting new counterweights on the carriers to finish the job under Mike's supervision.



Mike and Bill Luth start pulling the targets out of the shed. Bill is 75 years young and celebrating his 56th wedding anniversary tomorrow. A day at the range among friends today and home tomorrow; Bill has his priorities straight! He hauls targets out and we discuss rebuilding the target frames as was done last week at the Phoenix Rod & Gun Club across town.

Jack Arnold is hard at work getting targets into the carriers, wedges pounded in and everything safe and ready to go.


It's early but the wind is already blowing hard. Those clouds in the sky are a real rarity here as well. There's even some rain in the forecast, but I suspect the few drops on my windshield earlier this morning might be all the rain we see - as the day goes on that prediction turns out to be correct, the sky clears quickly but the wind sticks around all day.

Looking back towards the firing line from the pits, some unusual morning haze to go with the clouds. The Valley is essentially a desert, though not without some vegetation. There's rarely much moisture in the air, though.

A look to the east from the pits towards the mountains, the Lost Dutchman is out there somewhere - along with his gold mine. I think I'll put my efforts into mining 10's and X's today and leave the gold prospecting to the dreamers.

The pit work concluded we go back to the firing line to get everyone checked in and squadded. Mike handles registration and I do the squadding, in about 20 minutes we have thirty shooters all set to go on three relays. Another big F-Class turnout today, especially F-TR. We're happy to have all the new shooters and it's very gratifying to see them developing their shooting skills quickly. We place a high priority on helping new shooters develop so that they'll remain interested and pass those skills along themselves. If your match doesn't have new shooters, it's dying!

We have a roof over the firing line at 500 yards. Sun, not rain, is our concern; during the summer, when it's 115 degrees a bit of shade makes the difference between being able to shoot or not. No worries today, the morning is relatively cool and we're not expecting too much heat.


Relay 3 to the pits, relay 2 scoring and relay 1 on the firing line - time to get to work. The CSS tubegun is working smoothly, the ammo is giving me a bit more elevation that usual. I changed bullets from the old reliable Lapua 185 FMJ to Sierra 180's for this match. Maybe I should have bumped the charge a bit... A little later in the day a partial head separation on one case tells me the brass is getting a bit long in the tooth. Oh well, I prepped new brass last night; I hadn't planned to use it for a couple more months, but it looks like the time has come.
There's nothing like a big booming .30-06 on a Saturday morning! At one point I shoot 12 X's out of 14 consecutive shots, finishing that string with a 199-13X. There's still some life left in the Springfield Armory's century-old cartridge design.



Oliver Milanovic in the red and black shirt is one of our new shooters. His scores would make you think he has years of experience, though; he's made very fast progress and has been shooting a .300 Winchester Magnum lately. Talk about a boomer! Oliver brought his friend Hussein with him today, that's just what we want - spread the word, bring a friend, keep it growing! Hussein struggled a bit in the beginning and got a cut eyebrow from the scope. We'll blame Oliver for not warning him! Everyone got a chuckle and Hussein felt properly initiated as stories of cut eyebrows were the main topic of conversation in the pits when we went there.
Doug Frerichs and I went to the Rocky Mountain Palma Match at Raton, New Mexico last month. I have a golf ball for a bolt knob on my Palma rifle and Doug developed a bad case of bolt knob envy. On a trip to the local auto parts store he found a shift knob that was just the thing so he could say "Mine's bigger". Whatever it takes, eh?! Doug said the big knob made that 4 lug RPA 2000 a lot easier to close. It must have worked, Doug opened up with a solid 199 and was right in the lead pack, eventually finishing second for the day.


In the pits - Jim Cobb and Doug nearby. It was still cloudy when we began our pit stint, but the weather cleared up quickly about that time. Jim was shooting his Winchester M70 in 6XC and was also in the thick of it. Doug, Jim, Phil Hayes and I were essentially the lead pack in the Match Rifle category. At this point, I didn't know what was happening in F-Class since they were on the other end of the firing line.


Blue skies made their arrival and a pair of bullets impact simultaneously on points 2 and 3 kicking up some dust. Last week an errant lizard in the impact area was in the wrong place at the wrong time and didn't survive. No casualties this week.


Back on the firing line a bit later after pulling three strings. Service Rifle shooter Brent White, gets ready to go. Shooting, scoring, or pulling targets makes up the day, no rest periods. Bring plenty of water and some light snacks.




Scott Harris brought his son Sean and their friend Max out for their first match. The boys shot an AR15 in F-TR and had plenty of fun. They loaded their ammo for the match under Scott's supervision and while they may have found it tedious at the time, today they were all smiles and liked the fact that they shot with "their own ammo". Craftsmanship, pride in a job well done, laying your hands on the iron - all good life lessons that can be learned through competitive shooting.

Scott and Sean.



Here's Max enjoying his first - but not last - rifle match.



Bob Baird comes to the Valley from Bullhead City on the Colorado River a stone's throw from California. This time he had a new stock for his Savage, a Competition Shooting Stuff S1 stock and he won the F-Open category - smiles all around, Bob is a great guy and it's wonderful to see him take the win.



Today's match winner was Phil Hayes. Phil is a great shooter, whether it's with a match rifle, a service rifle or even F-Class - if it has a rifled barrel, Phil can shoot it well. His .308 tubegun didn't miss a beat and his 598 was well earned under today's conditions.




A look downrage from the firing line. It was windy with ocassional reversals of direction and a good fishtailing wind from behind most of the day. Our ranges aren't like the ones back East with lush grass and trees that make you think you wandered into a golf course, but scrub brush and Saguaro cactus makes us feel right at home.




F-Open winner Bob Baird with F-TR top 3: Jared Larson (2), John Chilton (1) and Chuck May (3).


The last shots have gone downrange, the targets are stowed, the standings read out, it's time to head down the road for some pizza! A quick 4 mile trip down to Papa Kelsey's Pizza should take care of the hunger pangs and give us a cooler place to chat than on the range.



Papa Kelsey was a rodeo cowboy for many years and the restaurant is decorated with rodeo memorabilia and posters. Not the usual pizza place decor, but this is Mesa: the Valley's feisty holdout against too much civilization. By the time I took this picture we were down to the last few stragglers, but it was a lively lunch as we hashed over the day's events and planned our upcoming new shooter training clinic.



The drive back north takes me through the Salt River - Pima - Maricopa Indian Community. Agriculture is an important part of the economy on the reservation and they have the water rights to make it possible. That much green isn't something that occurs naturally here in the Sonoran desert.





I take a detour to stop for a visit with Bob Jensen. Bob will be celebrating his 80th birthday next week and just got home from Camp Perry, over 50 years of going to the National Matches. Bob personifies the word Rifleman, there's so much I could say about him that it would fill a very large article, and it may one day. For those who don'tknow him, I'll just say that Bob has dedicated his life to the business and sport of shooting. Among his many wins at Camp Perry over the years, his Wimbledon Cup win in 1977 with a 200-10X stands as his most memorable. Bob shot that match with a Model 70 in .30-.338 and he still has the rifle in the safe. Note the Wimbledon Cup plaque above the medal display and his Distinguished Rifleman badge right in the center.

This year, Bob shot a 195-11X in the Wimbledon with a 6.5-284 Model 70 and he was thrilled that he had more X's now than when he won it. Bob has another .30-.338 Model 70 that has never been fired, he's thinking of making it into an F-Class rifle. Do you suppose he likes Model 70's? About 20 years ago, Bob undertook a project to duplicate the pre-64 Model 70 for commercial sale. The project was never easy, but after a great deal of effort and expense, the actions were ready for production and were every bit as good as the originals. For a number of reasons, the actions never made it to market, but Bob kept a few which he gave to friends and last year he took the very last one and put a .308 barrel on it for Palma shooting. The Model 70 has long been called the Rifleman's Rifle; Bob is the only Rifleman who has gone so far as to make his own Model 70's - the ultimate Rifleman.

Among the many projects Bob has undertaken over the years, creating the ammunition for the 1992 Palma Match was one of the most rewarding. Until then, the Palma was shot with military ball ammo. That year, the US hosted the match at Raton and the NRA asked Bob to produce 500,000 rounds of match ammo. That resulted in the creation of the Sierra 155 Palma bullet and an enormous undertaking to develop the load and load that much ammo. Palma shooting changed dramatically as a result of that project. Bob and I are working on an article about this which I hope to publish soon. Below is a picture of Bob signing a box of the 1992 Palma ammo for me. Just another thoughtful gesture by one of the true gentlemen of the shooting world. You can believe this box isn't ever leaving my sight!











This article began with a few musical references, and I'll finish with one more: the last line from the song "Signs" (Five Man Electric Band, 1971).
"Thank you Lord, for thinking about me, I'm alive and doing fine."

Equipment: Stiller Diamondback Action

Stiller Precision Firearms Diamondback Action
by Germán A. Salazar

This article originally appeared in Precision Shooting


Stiller Precision Firearms (SPF) in Wylie, Texas manufactures a number of actions directed principally at Benchrest competitors, but also suitable for position shooting, varmint hunting and other precision applications. The company’s founder, Jerry Stiller, is a licensed Professional Engineer and brings a very strong background in design and manufacturing processes to the rifle action world. The bulk of his career has been spent designing state of the art infrared defense equipment for the military. Structural design, metallurgy and processes are his specialties. With a background in the design of military hardware, Jerry is very aware of the processes and methods that need to be designed into hardware that must survive and work flawlessly. He also believes in buying the best equipment needed to complete the job. It is almost impossible to make state of the art parts on outdated equipment; at least if you intend to make a profit while doing it. The hard anodizing on the aluminum action bodies and industrial coatings on all bolts are just two examples of Jerry’s training in the defense industry. Why leave anything bare, when a good coating can be applied to make the part better. Master Machinist Curtis Helton and Office Manager Vickey Alley complete the SPF team.

Our focus in this article is SPF’s newest action, the Diamondback. Like many of today’s custom actions, the Diamondback is somewhat derivative of the Remington 722/700 design; however, no parts are directly interchangeable. The Diamondback is a stainless steel, two front lug, cock-on-opening, turn bolt action that uses a Remington pattern trigger attached by an aluminum trigger hanger. It is made in the buyer’s choice of right or left side bolt and right or left loading port configuration. An available option is the Drop Port for case ejection; this is the model photographed for this article. For ease of reference, as there are a few differences in specifications, we will refer to the Standard Diamondback and the DP Diamondback as needed.


The Receiver
The Diamondback receiver has a closed top surface to maximize rigidity and maintains a 1.350" diameter throughout its length; the rear bridge is full diameter and not flattened like a Remington. The receiver is drilled for an indexing pin on the front shoulder surface, allowing the gunsmith to pin the recoil lug in place, ensuring a perfect fit back into the bedding after a barrel change. However, the receiver also has a flat surface on the rear of the tang which may be used as a recoil surface for those who prefer to avoid the bracket type recoil lug. When barreled for the PPC or BR cartridge, this flat provides an adequate recoil surface, especially if the action is glued into the stock rather than being conventionally bedded.


The barrel tenon is a common benchrest size and pitch. 1.0625 x 18 tpi is used on all of the SPF benchrest actions except for the larger Python. A headspace of 1.115" was chosen to be the same as the Panda. Most gunsmiths are used to this number and a barrel fitted to a Panda will generally screw onto the Diamondback. A small change to the cone is all that is usually necessary if you happen to have a favorite barrel handy for your Stoelle action. All the newer SPF actions use a little deeper bolt face than the Stoelle to aid in actions fitted with ejectors, and that is the reason the cone change is needed.

Scope base mounting is handled by way of four 6-48 screws set in pairs on 0.860" centers with the pairs themselves on 4.23" centers. The rear scope base screw holes are blind but the front holes are drilled through the receiver (as is normal industry practice) so the gunsmith must ensure that the screws don’t bottom on the barrel thread. Action bolt are 1/4"x28 tpi and are located 1.375" and 8.000" from the face of the receiver. Bolt size and spacing is the same among the various SPF actions, such as the Viper and Rattler and is also common to the Stoelle action line. Stocks inletted for the Stoelle Grizzly will accept the Diamondback with minimal (if any) modification.

The loading port is of sufficient size to allow easy loading and extraction without unduly compromising the rigidity of the structure. Cases from PPC size through .308 can be quickly loaded and removed. The port is beveled on the front and rear part of the opening.


Overall, the Diamondback receiver is a strong, attractive and functional item. Roll marks are well executed, with the Diamondback logo as well as the serial number and maker’s name on the side opposite the loading port. At 32 ounces (without trigger or scope bases), the action is designed to allow the gunsmith to meet the 10.5 lb. weight limit of the Light Varmint and Sporter classes of Benchrest competition using standard LV taper barrels and commonly available Benchrest stocks and scopes.

Trigger
The Diamondback uses a conventional two-screw hanger to mount the trigger. The hanger and bolt cocking piece are designed for a Remington pattern trigger, the Jewell being the most commonly used competition trigger of this type today. However, Stiller has recently developed a mechanism allowing the use of an unmodified Anschutz 5018 trigger, a development that should make the Diamondback (as well as other SPF actions) more attractive to position shooters, whether 300 Meter, Palma, or anything in between.

The Bolt
The bolt body has eight helical flutes and two gas relief ports. The handle is TIG welded on which should eliminate any possibility of the handle coming off as can happen with a brazed or silver-soldered handle. TIG welding is the best form of welding available for this process, as the heat control and joint quality are significantly better than MIG or gas welding. Once TIG welded, the bolt is basically one piece, but much easier to manufacture than if cut from a single billet. The bolts are heat treated after welding, cleaned up, finish cut, hand lapped and coated with Armolly, a proprietary coating similar to hard chrome to offer protection from corrosion as well as smoother functioning. Each bolt is serial numbered to the receiver.


Another innovation in the SPF line of actions is the small firing pin. Jerry settled on the 0.062" diameter pin after much research and analysis. The problem with the larger pins is that at higher pressures, the primers often pierce, actually, they blank to use the correct term. As the pin diameter gets smaller, the area of the primer that pressure acts upon goes down exponentially, and so does the shearing stress in the primer. The Remington 788 used a 0.058" pin. The M16 uses a 0.062" pin. After reading some design docs on the M16, talking with Federal and CCI and completing some finite and classical structural analysis, the 0.062" pin was set. It is a very rare instance where a primer blanks on an SPF action.

The Standard Diamondback is offered with a Universal boltface that accepts PPC and .308 size cases. SPF also offers the Diamondback with either a .223 or a Magnum size bolt face. The drop port design requires that a PPC or .308 bolt face be specified rather than the universal .308 size. That small loss of flexibility is acceptable to most Benchrest competitors who tend to have a distinct preference for one case or the other; typically PPC for the 100 to 300 yard competitors and BR for those competing beyond 300 yards. Drop port actions must be used with either a standard PPC case or a BR case up to the dimension of a 30 Dasher (long 30 BR).

The Standard Diamondback bolt nose is coned at a 30 degree angle for ease of feeding and a sliding plate extractor is fitted to the front of one of the lugs (which lug depends of the bolt/port configuration specified). The DP Diamondback has a flat bolt face and a Remington extractor. However, the DP has a specially designed feed ramp for the PPC and BR cases to ensure positive and snag-free feeding. The locking lugs of both models are of conventional Remington form, located at the front of the bolt, 180 degrees apart and at 90 degrees to the bolt face. Stiller cuts a small radius into the junction of the bolt body and locking lug to reduce stress concentrations at this point; a sound engineering practice.

Ejection – Drop Port
The ejector fitted to the Standard Diamondback (when requested) is of the spring-loaded plunger type as used in many actions today. All of these plunger ejectors trace their design back to Mike Walker’s Remington 721 design of 1948 in bolt action rifles and to John Garand’s M1 before that. It is a simple and reliable method of ejection; however, something new is also offered by Stiller. A genuinely unique feature of several of the Stiller Precision actions, including the Diamondback, is the optional Drop Port ejection system designed by Jerry Stiller with inspiration from Benchrest competitor Jerry Hensler.

In the DP action, the loading port remains in the conventional location and a small ejection port is cut into the bottom of the action. The drop port allows the Benchrest competitor to speed his loading process by eliminating all handling of the spent case while a fresh round is loaded. The sliding plate extractor is deleted and a Remington extractor is fitted to the bolt face. No ejector plunger is used in the Drop Port. The extractor holds the cartridge case at the 6:00 position during extraction and gravity releases it into the drop port as it passes over. Given that gravity is a more reliable force than a spring, this is a nearly foolproof ejection system.


Normally a towel or a box is placed on the bench under the port to prevent the spent cases from being damaged by the concrete bench top. The DP design neatly addresses the two concerns that some competitors have regarding case ejectors: 1. that the ejector plunger places an asymmetric load on the case when chambered; and 2. that the ejected case will be thrown with such vigor that it will roll off the bench and be damaged. The concept of gravity driven, bottom ejection on a bolt action rifle is so novel that Jerry applied for a patent on this feature and as of this writing it appears likely that it will be granted by the US Patent and Trademark Office.

SPF actions are generally acknowledged to have easy extraction as compared to other Benchrest quality actions. Most other action makers cut the extraction surfaces with an end mill in a single setup. This tends to give an extraction that is not very linear and harder at the end of the stroke. On the SPF actions, the extraction is easier because the surfaces are generated on the CNC 4th axis rotary table with true matching surfaces on the action and bolt. This allows the extraction effort to be very even and not as hard as on actions made by other methods.

Rigidity
In this analysis, as always, I received invaluable help from Wes Grass who handled the computer modeling and calculations. We continue to use Stuart Otteson’s methodology for calculating action rigidity (see Benchrest Actions & Triggers, Stuart Otteson, 1983), but using the Solidworks computer program. All rigidity figures are calculated through a section across the width of the action at the center of the loading port as in most cases this will be the weakest area of the action. Following is a table showing our calculations for the rigidity of various modern rifle actions including our subject:

Remington 700 0.54 x 106 in2-lb
Winchester Model 70 1.11 x 106 in2-lb
Remington 40X 1.38 x 106 in2-lb
SPF Diamondback 3.16 x 106 in2-lb
Stoelle Panda 3.52 x 106 in2-lb
Barnard S 3.93 x 106 in2-lb
Gilkes-Ross 3.97 x 106 in2-lb
Hall B 10.7 x 106 in2-lb



Sectional View - Stiller Diamondback

Winchester Model 70, Stiller Diamondback, Remington 700
We make no attempt to answer the question “How much rigidity is enough?” nor is it our purpose to pursue the answer. Each action maker and each customer must evaluate the available choices of materials and design and decide what value he places on rigidity versus cost, weight, size and other features. Our objective is to present these figures in this and future articles as a basis for comparison of a single element in action design, not as a conclusion of any sort.

Stiller Precision’s Diamondback action presents the competitive shooter with a well made action that includes some innovative features designed to make the action more durable, more reliable and to ease operation. It fits the inletting currently offered by many stock makers, simplifying the stocking operation for Benchrest competitors and it accepts widely available triggers. Overall, this action is an attractive option for many forms of competitive shooting and is sure to further enhance the already sterling reputation of Stiller Precision Firearms.

Specifications
Length: 8.5 inches
Weight: 32 ounces
Receiver Material: 17-4 PH Stainless Steel
Receiver Hardness: Rockwell C 38
Receiver Diameter: 1.35 inches
Loading Port: 3.00 inches long x 0.650 inches high
Bolt Material: Premium S-7 Tool Steel
Bolt Hardness: Rockwell C – 40/42
Bolt Diameter: 0.706 inches
Bolt Face & Counterbore Depth: 0.135 inches, 30 degree cone (standard)
0.150 inches, Remington type nose (drop port)
Bolt Locking Lugs: 2
Bolt Rotation: 90 degrees
Bolt Travel: 4.0 inches
Firing Pin Fall (to impact): 0.220 inches
Lock Time: 2.4 milliseconds
Diameter of Striker Tip: 0.062 inches
Barrel Shank: 1.0625 inches dia., 1.115 length, 18 TPI
Bolt Face to Receiver Shoulder: 1.115 inches
Manufacturer: Stiller Precision Firearms LLC
2405 Country Meadow LaneWylie, TX 75098
mailto:stiller@viperactions.com
 

All contents Copyright 2012 The Rifleman's Journal