Cartridges: Reloading the .303 British Today

Reloading the .303 British Today
by Germ├ín A. Salazar

The .303 British originated in the 19th Century, 1888 to be precise, as a black powder cartridge loaded with a 215 grain round-nose bullet. Notwithstanding its Victorian origins, early in the 20th Century the .303 successfully made the transition to smokeless powder and spitzer form bullets. In that form, it served the Commonwealth through two World Wars - not to mention a century of target shooting. The .303 British remains a perfectly useful rifle cartridge today, although it isn't very often seen on US target ranges. However, since I sometimes like to shoot a vintage rifle and the .30-06 is my principal target cartridge, a 1903 Springfield doesn't seem too "vintage" to me; therefore, I have a Lee-Enfield, albeit a fairly modern No.4 Mk II made in 1955.

Like many other current owners of any of the multiple versions of the Lee-Enfield rifle, I enjoy shooting this round and have always reloaded for it as I generally have no interest in shooting factory or arsenal loaded ammunition. Reloading the .303 isn't fundamentally different from any other bottle-neck rifle cartridge, but there are some special considerations brought on by the rimmed case design as well as by the rifles in which the .303 is usually chambered.

If we look beyond the cartridge's history for a moment and simply look at its physical characteristics, we see a case of volume similar to the .308 Winchester and a bore diameter just a few thousandths of an inch larger. However, it would be a mistake to assume that this cartridge can loaded to be a ballistic twin to the .308; it can't be loaded that hot because the rifles chambered for the .303 are not built to withstand pressure levels used in the .308. Whereas the .308 is loaded commercially to a maximum average chamber pressure of 55,200 c.u.p. (copper units of pressure), the .303 is limited to 45,000 c.u.p. and handloaders should be very cognizant of that limitation as it is essential to safe operation of these rifles.

Military brass for the .303 British isn't particularly easy to come by in the US these days, so most reloading will be with commercial brass. In his excellent Pet Loads article on the .303 British many years ago, Ken Waters noted that there is a very large difference in case weight and consequently case volume among the various commercial and military makers of .303 brass. Ken noted brass weight between 162 gr. and 190 gr. for various types of brass.

Because this article, unlike Ken's, doesn't provide specific load data, I won't go into case capacities by brand, but will caution you to check your brass if you plan to load in more than one make or lot of .303 brass as the differences can have a significant effect on pressure. I have IVI, R-P and S&B brass for my .303 and I certainly agree with Ken's caution as to the widely varying capacity among them.

As with any other cartridge, I recommend full-length sizing for the .303. However, because the .303 uses a rim for headspace control, unlike more modern designs that use the shoulder, we need to discuss case sizing a little. In a rifle chambered for a rimmed cartridge, headspace is the difference between the rim thickness and the space provided for the rim between the breech face and the bolt face. The case shoulder does not contact the chamber shoulder when the case is chambered. Although the shoulder should be set back in resizing, it should be a minimal amount - just enough to avoid hard bolt closing. Resizing in this manner will maximize case life.

The uper case is new, unfired. Note how much the shoulder has blown forward on the lower (once-fired) case.
Because the .303 British uses the rim for headspace control, many chambers, especially those in military rifles, have a very long rim to shoulder dimension, allowing for significant shoulder displacement on firing. If you set up the resizing die to touch the shellholder in the press and thus push the case shoulder all the way back to the original position, the case will separate after only a few firings, perhaps as few as two firings. My best advice is to use a case gauge to check the amount of shoulder setback and keep it to a minimum. This will require raising the die a bit in the press, and it might not size all the way down, but if the bolt still closes without undue effort, that's OK.

Despite my deep interest in primers, this is not an application in which the primer is going to make a meaningful difference. Primer variance is most noticeable at longer ranges, and for my purposes today, the .303 is something that I shoot at 300 or 500 yards, maybe 600 once in a very long while, so the subtleties of primer performance aren't really high on my list of reloading priorities. Add in the fact that it's been at least 20 years since I was able to generate a clear sight picture on a post front sight and you can see that primers just aren't that critical to me in this application!

What is important it that you select a primer with a tough cup as both the firing pin impact and protrusion from the bolt face are somewhat greater with many Lee-Enfield rifles that they are on more modern bolt action rifles. I tend to use Winchester primers in my reloading for the .303 and they have always worked well, although CCI primers would also be an excellent choice.

Given the very occasional use that I give the .303, I prefer to keep my reloading very simple and thus only use one bullet, the 174 gr. Sierra Match King. The bullet diameter for the .303 British is 0.311" and although Sierra makes a number of bullets in this size, as do the other manufacturers, the 174 gr. Match King is accurate, readily available and perfectly suited to my limited use. You can look through the various reloading manuals from the bullet manufacturers to find other bullet weights in 0.311" or 0.312" and appropriate loads, but I'll stick to the 174 gr. Sierra Match King.

Even though we aren't going to load the .303 British to the same pressure levels as the .308 Winchester, many of the same powders that are commonly used in the .308 are well suited to reloading the .303 with similar bullet weights. To me, that means H4895, IMR 4895, IMR 4320 and IMR 4064. Although other powders in that burn rate range would also be useful, I would caution you to avoid double-base powders and other attempts to maximize muzzle velocity. In fact, muzzle velocity with the 174 gr. Sierra should be held to no more than the original 2450 fps in rifles that are in excellent mechanical condition and 2350 is an even better limit for accuracy work. If the rifle looks worn or questionable in any way, it's best to make it a wall hanger and find something else to shoot. Many of these rifles are well over 100 years old and have received widely varying degrees of care over the years; risking your eyes behind one for the sake of a few more fps of muzzle velocity is foolhardy. Gambling at a casino is fine if that's what you like, but don't gamble your eyesight!

That's about it for now. Later this week I'll take the rifle out and generate some mid-range targets with my loads and some old Mk VII ammo for comparison. However, because the Mk VII ammo has corrosive primers, I'll pull it down, replace them with modern non-corrosive primers and then shoot it. We might be sacrificing a bit of historical purity in the comparison, but my barrel is pristine and I intend to keep it that way!

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