30-40 Krag brass for the 303 British

[303carbine]

I had a few new Krag brass laying on the bench and decided to make some 303 Brit from it, one pass through the Brit neck die and a trim and it was done.
I seated a 174 grain RN bullet over 37 grains of 3031, it fire formed nicely and shot accurately as well.
I have done this in the past and the Krag brass seems to last longer than Brit stuff does for what ever reason.
Some reloaders I have talked to said the Krag brass is thicker at the web, this makes it last longer, along with the rim being possibly a bit thicker too that tightens up the headspace a bit.
I have some older Krag brass that have 5 reloads , the most full house loads I can get out of neck sized 303 brass is 3.

Information

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[browningautorifle]

Too bad. I have a couple of hundred .303 cartridges that I'd trade for .30-40 brass any time...

[Parashooter]

. . . Some reloaders I have talked to said the Krag brass is thicker at the web, this makes it last longer, along with the rim being possibly a bit thicker too that tightens up the headspace a bit. . .

They're handing you horsefeathers. Rim thickness specs and tolerances are the same for .30/40 brass as for .303. The Krag rim is a little wider, but that has no effect on headspace or longevity. If you want to (dis)prove the heavier web theory, just compare the weights of empty .30/40 and .303 cases after trimming to the same length. Some batches will be lighter, some heavier - but there's no predictable pattern.

Case life is affected primarily by firing pressure, chamber finish, and presence of lube between cartridge and chamber.

[303carbine]

Lubing cases?? I was always under the assumption that lubed cases are not good for any rifle.

[Parashooter]

If you want to (dis)prove the heavier web theory, just compare the weights of empty .30/40 and .303 cases after trimming to the same length. Some batches will be lighter, some heavier - but there's no predictable pattern.

Took a few minutes to weigh up some brass on hand. These are average weights from random 10-case samples of various .30/40 and .303 Brit., empty with spent primer, normal lengths (.30/40 not trimmed to .303 spec) -

Caliber - Maker - Average weight (grains), case with primer
.30/40 - R-P - 167
.30/40 - WW - 173

.303B - R-P - 167
.303B - WW - 167
.303B - FC - 173
.303B - Norma - 179
.303B - PPU - 173
.303B - WRA - 179 (1943 headstamp)

Get the idea?

[Eaglelord17]

From my understanding lubing cases places all the pressure on the bolt instead of some of the friction of the case being held on the chamber wall. I never knew it could have a effect on case life though, I am very interested in this (might be good for my nice and strong P14 action).

I know some rifles required lubing though, like the Paterson rifles, or the Swedish would lube there AG-42s to help extract there higher pressure rounds.

[Parashooter]

I said "Case life is affected primarily by firing pressure, chamber finish, and presence of lube between cartridge and chamber." I did not say "Lube your cases for firing."

If you believe your rifle's action strength is so marginal that a 10-20% increase in "bolt thrust" resulting from diminished case/chamber adhesion will damage something, you should probably re-examine your decision to fire it at all (especially in the rain).

If you suspect that varying conditions of case/chamber adhesion may have a detrimental effect on accuracy, you might want to ensure your cases and chamber are uniformly clean and dry before shooting.

[ireload2]

Use a cartridge case as a mechanical brake stretches the case at the junction of the solid head if the action is springy and the case grabs the chamber.

For longer case life use a more rigid action.

Using a case as a mechanical "brake" in an effort to protect your action means the action is not highly suited for reloading expecially loading to factory pressures.

[ireload2]

About 20 years ago both RP and WW brass measured .455 to .456 diameter just in front of the rim. I had a large batch of WW brass cut off for the .455 Supermag grrrrrrrr. They measured .455.
I had a dozen or so of old RP .30-40 brass and they were the same size. I also found 50 RP cases at gunshow that measured the same (I take a mike to gunshows)

I have talked to a few shooters that tell me that current RP and WW Krag brass is .451 to .452 just like the .303 brass made by the same companies.
However PPU .303 measures .454 to .456 and does not create such a huge step when fired.

While the specs may say the same thing or maybe not you have to check the actual brass to know the diameter at the head.

[303carbine]

I just measured the new unfired Winchester 30/40 Krag brass I have.
it is 11.43 mm at the base.

303 British
Federal 11.38 mm.
Imperial 11.43 mm.
Winchester 11.40 mm.
Remington 11.41 mm.

So if you have a 303 that has a generous chamber, the little extra the Krag brass is a good thing.
The older Imperial stuff is closest in measurement, all brass measured was new unfired.