Cartridges: Lapua Small Primer .308

Lapua Small Primer .308 Brass
by Germán A. Salazar

We've all seen the recent reports about the new Lapua small primer .308 brass.  The old saying "You can't know where you're going if you don't know where you've been" is very applicable here; let's review the history of small primer .308 brass. 

My first reaction to the announcement of the new Lapua brass was "old news" as this brass does not appear to be different in any material way from the Remington small primer .308 brass which I've worked with quite a bit in the past.  I still have several hundred of the Remington and I don't use it because I've never found a performance improvement with it at long-range despite significant amounts of testing.  When Remington made their small primer brass, it was intended to be reformed into .22 BR, 6 BR and 7 BR, in fact some of the ones I have are even headstamped .22 BR.  The small primer is adequate and correct for the BR capacity but not necessarily for the full-length .308.  Remington did not intend for this brass to be used for .308 shooting.

If you've read my primer articles (small primer article, large primer article), you will recall that the fundamental conclusion was that the best primer was generally the primer which had the lowest flash level and produced the lowest muzzle velocity.  All of this, of course, assumes that the primer provides enough energy for consistent and reliable ignition.  Primers are an excellent example of what I like to call the Goldilocks Conundrum: finding the "just right" point along an imprecisely defined continuum.  In this case, the continuum of ignition energy to be applied to the powder charge. 

Simply stated, the small primer in the .308 case is at the low end of acceptable ignition under ideal conditions - and conditions are often not ideal.  As ambient temperature drops and especially if ignition systems are modified (uselessly, I might add) with lighter firing pins, ignition reliability declines.  A system which is marginally acceptable under ideal conditions will then begin to produce hangfires and misfires.  In many cases, when shooters used the Remington small primer cases as a full-length .308, this is exactly what happened.  Heavier powder charges and slow-burning powders further add to the difficulty of ensuring reliable ignition.  With the typical Palma load of 46 grains of Varget, a moderately slow powder, I will venture to say that many small primers will be inadequate to ensure adequate ignition under all environmental conditions.

Before the arrival of the Russian primers, most large rifle primers were more powerful that was necessary for a .308 case and a reduction of primer energy could, in some circumstances be beneficial.  However, most of the shooters who used the Remington small primer brass, after experiencing some ignition trouble, switched to the Remington 7 1/2 (if they kept using the brass at all).  The irony of this is that the Remington 7 1/2 primer produces more flash than almost any large rifle primer; yes, it is a small primer that produces more flash than most large primers!  Go back to the primer articles and look at the pictures.  In essence, by switching to the Remington 7 1/2, these shooters were returning to a large primer level of ignition energy.  Today, we have an excellent small flash large primer - the Russian - which has, in my considered opinion, eliminated the problem of too much flash in the .308 case without introducing the problems of too little flash.  It is the Goldilocks primer for the .308 and similar size cases: just right.

The only truly successful use of the Remington small primer brass which I am aware of was by Bob Jensen who used it for 300 yard rapid fire loads.  Bob had a fairly light load for rapid fire, knows primers well enough to have selected a reliable and mild primer and shot the brass only in the summer months.  The small primer kept ignition consistent with his mild load and he fired many very high scores with the small primer brass - in 300 yard rapid fire.  Tellingly, however, Bob did not use the brass for his 600 or 1000 yard .308 ammunition at the time and he certainly didn't specifiy it when he was tasked with loading 98,000 rounds of .308 long-range ammunition for the US Army Marksmanship Unit or when he loaded 300,000 rounds for the 1992 Palma match.  Those long-range rounds all used regular Winchester large primer .308 brass.  Now we are being told that small primer .308 brass is the latest, greatest thing for long-range shooting...

Lester Bruno gave me 24 pieces of the new Lapua to try out and I intend to give them a good trial.  Given that Lester had a grand total of 29 pieces on hand, this was a very generous offer and I appreciate it!  Selecting the correct primer for them is really the biggest part of the testing because the entire purpose of the project is the use a primer which is milder than a good large rifle primer while still producing enough energy to reliably ignite the charge.  As an initial matter, I suspect that the Russian small rifle primer will be too mild and the Remington 7 1/2 too harsh (it always is).  I have some Federal 205 Magnum (yes, 205 Magnum) primers which have always tested consistently and are relatively mild, though not as mild as the Russians.  My concern over using these for the testing is that they are no longer available so the test becomes useless.  The CCI BR4 primer is just a tiny bit stronger than the Russian, and it contains aluminum particles which disperse through the powder charge to aid ignition.  The lack of those particles is one of the Russian primer's great aids to consistency, but in this case, they might be of some value.  The standard Federal 205 might also be a useful choice, though the lot to lot variance on these is more than other brands.

Later today I will post some basic weights and measures on the new brass.  This will include weight and variance, neck thickness and variance, case body wall variance (as measured with the Audette tool).  I will shoot them this weekend at 1000 yards, side by side with my normal large primer brass and report back as well.  At some point, hopefully soon, I'll do some chronograph testing of the brass with a few different primers, but I don't know how soon I'll be able to do that.  In any event, I'll post my findings as they develop.

Case Weight and Variance
I weighed 20 of the cases on my Ohaus Navigator scale, the lightest weighs 173.7 gr. and the heaviest weighs 174.6.  All but the one lightest case are between 174.0 and 174.6, for my purposes, this is very uniform brass in terms of weight.  I wouldn't bother to sort it on this basis.  Modern Winchester brass typically weighs 155 grains, so this brass is distinctly heavier (although the same as Lapua's large primer .308 brass) and I will have to adjust my load somewhat to compensate for the reduced internal capacity.  I'll check capacity before loading and decide on the appropriate adjustment.

Neck Thickness and Variance
I measured case neck thickness with an electronic Mitutoyo ball micrometer.  Case necks were relatively uniform, with most cases exhibiting just over 0.001" variance in thickness around their circumference.  Typical thickness was 0.0142" to 0.0152" per case with some going a few tenths thicker or thinner.  Since I neck turn all my brass, this doesn't especially bother me, but I expected the variance to be somewhat lower.  Maybe my expectations were too high.

Case Body Thickness Variance
Using the Audette tool, I checked the cases for variance in case wall thickness 0.250" up from the inside of the base.  Frankly, I was very disappointed with this result.  The cases average 0.003" variance which is right on my reject point for this measurement which I consider this to be the most important measure of case uniformity.  Only four of the twenty cases measured were under 0.003" variance and more than that were over 0.003".  My Winchester .308 brass rarely hits 0.003" with most falling between 0.001" and 0.002"; even the Winchester and Lapua .30-06 brass is usually in the 0.002" range.  Why this brass is distinctly worse, I don't know as shorter brass is theoretically easier to draw uniformly.

Neck Turning
As I mentioned earlier, I need to turn the necks on this brass to fit my chamber which has a 0.336" neck diameter.  I turn all my .308 brass to 0.0125" neck thickness which produces a loaded neck diameter of 0.333" for 0.003" diametral clearance.  Turning this much off the necks is best done in two passes.  Tonight I turned them to 0.0136", that killed the charge on my little Craftsman power screwdriver.  I'll make the second pass tomorrow and then load them for the weekend.

Neck turning is now complete, all are at 0.0125"  to 0.0127".  That was a lot of brass to remove!

Flash Hole Size
As I was looking at the brass, I noticed the flash holes look small, real small.  The decapping pin from the Redding .308 die measures 0.062" diameter and will not go through the flash hole.  The decapping pin from the Redding 6BR die measures 0.057" and will go through the flash holes.  Looks like I'll be swapping decapping assemblies from the 6BR die to the .308 die in order to reload these cases.  Not a major hassle, but something to be aware of before reloading or you'll get the decapping pin stuck in the flash hole.  This problem was common with 6BR brass when it first came out, until Lapua and Norma slightly enlarged the flash hole.  Sinclair makes a little reamer just for that purpose; I'll see if it opens the flash holes just enough for the 0.062" pin, that would solve the problem.

I neck sized the brass to 0.331", primed with CCI BR4 primers and loaded with my normal Palma load, slightly reduced for the heavier brass.  I had to remove the decapping pin from the neck die and will have to decap with a Wilson PPC punch, but that'll be allright for a small quantity like this.  Of course I had to try one case with the decapping pin in place and predictably, it got stuck in the flash hole and had to be driven out.  Don't try it, the decapping pin is no substitute for the flash hole reamer. What is really needed, however, is for Lapua to actually drill the holes to 0.065" so that a 0.062" decapping pin will fit!

Shooting the new brass - finally!
Palma match in Phoenix today, so I took ammo loaded in the new brass as well as my normal load in Winchester brass.  The plan was to shoot the Palma with the standard load and then to fire an extra 15 shot string at 1000 yards with the new brass.  As things turned out, I was able to do exactly that and better yet, I was able to fire the two strings on consecutive relays after one of the shooters on my point dropped out.

Conditions were reasonably good, temperature around 65 degrees, good illumination on the targets despite a few clouds and wind in the 3 to 12 mph range.  While the wind was more that we'd like to see for ammunition testing, it's fairly typical for our area and reflects the realistic conditions under which we shoot Palma and under which this brass will have to prove itself.  I often had to make 3 moa to 6 moa corrections for consecutive shots as the wind velocity was changing quickly on both strings although it got a bit tougher with each relay.

I fired my first 1000 yard string on the second relay; this was with Winchester large primer brass and Russian primers, which gave me a 147-6X.  The was the top score on that relay and only beaten overall by a 148-4X and a 148-2X fired on the first relay.  My second string was with the Lapua small primer brass and CCI BR4 primers.  I shot a 146-4X which was the highest score on the third relay (the last of the day and the trickiest).  Both strings had comparable elevation dispersion and no elevation change was required on the sight between the two loads, so I must have made a reasonably accurate estimate of the powder charge change to keep velocity equal between the two types of brass.

My first impression, therefore, is that this was one heck of a lot of work for no noticeable improvement under typical Palma conditions.  Elevation dispersion was the same and the scores were about the same.  Increased risk of reduced ignition under adverse conditions for no performance gain under ideal conditions is a poor trade-off.  I'll shoot this brass again at least once, but I don't see any magic - not that I expected any.

For detailed primer testing information, please see the articles linked below:
A Match Primer Study in the 6BR Cartridge

A Match Primer Study in the .30-06 Cartridge

Update, August 2 -2010
I found this posted on a forum today, no surprise...

Well finally got my hands on the new Palma brass with the small primer, what a dissapointment. Loaded my normal load of 44.6 of 2206H (H4895) using CCI450's and 155 HBC,I use these primers in my 6BR with no issues, loaded the first round and pulled the trigger "click" !!! oh well maybe I didn't put any powder in that one (came home pulled the bullet and found I had filled with powder !!) put the next round in and pulled the trigger click BANG !!! and hit 3.5moa low @ 600M, went back to the LR brass with the same batch of powder and all is good,temp was about 18 deg C.


Has anyone else had this problem ?? I have read that there was a velocity drop of 20-30 FPS but 3.5moa @ 600 is more than 20-30FPS and the click BANG is a worry, thought and advice welcomed.
Thanks
Matt


Update, August 23, 2010
I shot the small primer brass for one string at 500 yards yesterday.  First I shot a string with Winchester large primer brass, PMC (Russian) primers, scored a 200-16X in mild conditions.  The next string with identical conditions, using the Lapua small primer brass yielded a 198-10X with double the elevation dispersion and two 9's which were completely off call.  I used CCI BR4 primers with the Lapua brass and the powder charge was adjusted to match the MV of the Winchester brass.

Update, October 13, 2010
The following was posted by Kevin Thomas of Lapua on the forum at http://www.accurateshooter.com/ (underlining is ours)  http://www.accurateshooter.com/forum/index.php/topic,3751998.0.html

[T]he flash holes on the new Palma SRP cases are indeed 1.5mm, as opposed to the more standard 2.0mm used on most of our other cases. We utilize the smaller (1.5mm) flash holes on a number of cases, all of which are primarily accuruacy oriented. The 220 Russian, 6mm BR and 6.5x47 are the others, with the 308 Palma being the latest. Yes, you will need to switch out your decapping pin in most 308 Win dies to avoid sticking a pin in the flash hole. Do apologize for the inconvenience here, but as has been pointed out, we were responding to customer's requests here, and it does indeed seem to work. There have also been several comments here about the potential reliability in cold weather, and we agree with those assesments. The cases were intended for competitive shooting, which is generally conducted in nice, warm, sunny weather (at least, that's the way I like it!). We discourage reloaders from using this brass for cold weather hunting, or heavy charges of slow burning, hard to ignite powders, because there is a real possibility of poor ignition, hangfires or outright failures to fire in such situations.

Kevin Thomas
Lapua USA

And another related quote from Kevin about the .308 small primer case:
http://www.accurateshooter.com/forum/index.php/topic,3725681.0.html
...you're perfectly correct that this is pretty much the outer limit of what a small primer can reliably ignite. To that end, we're marketing this as a competitive case, and not recommending it fro many hunting applications. Extreme cold temps or harder to ignite charges of slow burning powders could be a problem here with hangfires or that sort of thing. However, with the normal powders used for competition (such as Varget) and the conditions competitions are normally held under, this is not a problem. Give them a try, and see if they don't help reduce the variables I've discussed here.

Thanks,
Kevin Thomas
Lapua USA

I don't want to give the impression that I'm gratuitously bashing the small primer case, however, I think it bears emphasizing that the small primer carries with it the potential for misfires or squib ignition which can cost you a match and I have found no overwhelming performance gain (none at all actually) to justify risking a match in this manner.  This is simply another example of faddish trends and the prudent competitor would do well to stick to the well proven, time-tested large rifle case for the .308, whether Lapua or any other brand that you favor.  - GAS -

Update 01-04-11
I just saw the quote below on a forum and it really gave me a smile since I'm a big fan of Cheers.  I try to be as honest and straightforward as I can on any evaluation, but I suppose we all have biases.  In any event, this points to the possibility that the early batch of brass I got was not representative of current production in terms of wall thickness variance.  - GAS -  Here's the forum quote:
I think German is basing his experience on a bad lot of brass. He reported an AVERAGE of .003" wall thickness variation. Using my NECO and inspecting 100 cases, I found 2 with .0015" and those were the worst. The average for my batch was .0007".


German bags on these every chance he gets, but when he shot them the first time, I don't think he even worked up a load with them... new brass and new primers require at least a new load workup.

I am a huge fan of German's and am a religious reader of his blog, but he gave this brass short thrift. It reminds me of an old quote from Cheers, "I tried that positive thinking crap and I knew it wouldn't work and sure enough, it didn't."
Related Article
Large Flash Hole vs. Small Flash Hole Test
 

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