Reloading .303 cases

[Merc]

I reload .303 British cartridges and have been using PPU brass because the cases weigh more than cases made by some of the other cartridge manufacturers. From my own experience - 3% heavier than Remington Core-Lokt and 9% heavier than Winchester Super-X. The basic thinking here is the heavier weight translates to slightly thicker walls of the PPU case which should hold up better/longer than thinner cases if the cases are neck sized only and fired from the same rifle. The PPU cases I've fired show no sign of excessive stretching after multiple reloading.

Does anyone have any fired Mk 7 .303 British cases on hand? I'm curious to know how the weight of a Mk 7 case compares to the weight of a PPU case (in grains).

[Sunray]

Have some unfired(firing doesn't change the case weight), IVI, ball cases at home. Even know where they and my scale are. Be tomorrow.
Mind you, the weight of the PPU case only means they're a bit thicker than American commercial brands.

[Parashooter]

I think you'll find just as much variation among different makes of "Mk 7" cases as among commercial cases. When comparing weights, don't forget to take the extra mass of Berdan anvils into consideration. Here are some examples; the Berdan cases are once-fired and the Boxer ones retired after many loadings -



Note how sometimes a weight difference may be more influenced by the height of the solid web than by wall thickness. Compare, for instance, the commercial W-W case to the WRA 1943 (originally a "Mk 7" load).

It's a common error to think that thickness or weight is a primary factor in case longevity. Brass composition/hardness, chamber finish, action type, peak pressure, and presence/absence of lubricant can have far greater influence. One example -


(Case #1, fired dry, was so tightly stuck in chamber after separation that a chamber cast was needed to remove it. Loads were the same for both cases, as was the neck-only sizing operation.)

[Merc]

Parashooter,

Thanks for the interesting reply. I agree there are other things to consider that may affect weight and the wall strength of a case. But notice that the W-W Super case that experienced case-head separation in your illustration is a Winchester Super-X and is the lightest of the three cases I've been reloading.

My interest as a reloader of .303 British is to determine if any commercial ammo currently available comes close to the original dimensions or specs of the Mk 7 military case.

I noticed PPU's higher case weight difference vs. the others shortly after I began reloading and so I primarily shoot the reloaded and heavier PPU cases. I check every case for a stretch groove before reloading and haven't had to discard any so far. My No.4 head space is within military spec and I neck size only. I've probably reloaded some of the PPU cases five or six times.

What kind of lubricant is best to use on cartridges?

Merc

[Parashooter]

My interest as a reloader of .303 British is to determine if any commercial ammo currently available comes close to the original dimensions or specs of the Mk 7 military case.

Please understand that Mark VII ("Mk 7") is the designation for a complete round, not the case. Same case is used for earlier and later Marks. The WRA 43 Boxer case shown above is from Mark VIIz ammunition loaded in the USA for the UK during WWII, but it's very different from the Kynoch or Radway Green Berdan cases from Mark VII ammunition.

All commercial cases made to SAAMI or CIP specs have, within allowable tolerances, the same exterior dimensions as the military cases designed to fit normal military chambers. As you can see in the photo, there is some variation in interior dimensions.

The Berdan anvil adds mass, making direct weight comparison of Berdan and Boxer cases problematical. This is slightly mitigated by weighing primed cases (or adding a primer to the pan with unprimed specimens), allowing the Boxer anvil to be included.

Sample primed weight, grains -
K50 - 184
PPU - 178
F-C - 174
R-P - 165
W-W - 164

[Merc]

Parashooter,

Thanks. Great explanation. No. 4s are known for generous chamber space so it would be nice to be able to shoot a commercial cartridge that has the capability to stand up to all that expansion. The PPU brass has done it so far.

The commercial ammo that's available today in .303 British is somewhat limited, hence the reloading. I tend to keep my reloads lighter than factory loads and that probably helps with brass longevity but also lowered recoil and actually improved accuracy.

The lubricant that you mentioned - is it the same as the case oil used with full length dies? I have a wax lubricant that's also used with full length dies.

Merc

[blackhawknj]

IIRC isn't it possible to adjust headspace on Lee-Enfields by switching bolt heads?

[Art]

Often the problem that produces blown out .303 cases isn't excess headspace but rather war time chambers. Wartime chambers tend to be oversize which doesn't matter a whole lot with a rimed cartridge. The headspace on my old 1917 No I Mk III which I got fresh from FTR was measured by a gunsmith at .070 or quite OK, the fired cases look like classic examples of excessive headspace. The problem in this case isn't the headspace but the very generous chamber. Peace time rifles are another story, My No 4 Mk II which came new in the wrap produces fired cases that look like the came in a bag on new brass.

I full length resize because my hand loads will be used in both rifles. I have a bunch of brass from when I wasn't reloading but wasn't throwing any away either. Two reloads is max with me because of the chamber differences in the two rifles, and because I hand load to Mil Spec. velocities with 174 gr bullets.

[Merc]

I believe it is possible to adjust head space with different bolt heads. Not real sure if it's a direct replacement meaning it may take an experienced 'smith to get it right. I saw a #3 bolt head on eBay a while back. Never saw one before and probably won't see another for quite a while. Asking price was $175. Lots of #1s and #2s on eBay and dealers sights.

Remember that .070" is the commercial head space field gauge dimension and .074" is the military head space field gauge dimension. My No. 4 closes to about 80% on a .074" gauge and closes completely on a .070" gauge but still shoots the heavier neck sized brass with light loads well without becoming over-stretched. I'll continue to reload the same cases until I start to see stretching problems starting to occur.

Merc

[Merc]

Art,

I have a tendency to shoot what ever they have on the shelf at my local Cabelas, in my case, it was 150 gr flat base SP bullets. They seem to do really well with a starting powder load plus 1 gr. of BLC-(2). I recently ordered a box of 174 gr boat tail FMJ bullets just to try something different.

Merc