30-40 Krag brass for the 303 British

[Parashooter]

Any base diameters from .452" to .460" are within SAAMI .303 specs. (.30/40 spec is .001" greater.) What size comes out on a specific production run simply depends on the finish production die's history. New die: small base - worn die: large base. Trying to predict what you'll find in the next batch you buy based on the kind of small sample most of us enthusiasts have available is an exercise in futility.

303carbine, CIP maximum cartridge base diameter (P1) for .303 British is 11.68mm. With a tolerance of -0.2mm giving 11.48mm minimum, your figures of 11.38 to 11.43mm seem low. Is it possible you aren't measuring immediately adjacent to the rim or your caliper needs calibration?

Attachment 64101

[ireload2]

Parashooter
My micrometers (I collect micrometers) are in calibration. An 0-1 micrometer is calibrated by closing the spindle on the anvil and it should go exactly to zero. If I were to suspect a problem I also have a set of .251 to .500 gauge pins in .001 increments. I use micrometers much more than any of my rifles- about 45 years of professional use in manufacturing and engineering.
No matter what the specifications say the specification is not the part that is chambered and fired. I first started reloading the .303 about 1969 and most of the brass I have used during that time has been WW, RP and Federal along with some smaller numbers of other brands. I have checked many brands of .303 British brass. Herter's. Interarms, Norma, RP, WW, Imperial, British millitary, 1943 WRA made in the US. RP and WW are always about .451 to .452. I have also made .303 from .30-40 Krag, .444 Marlin and .405 Win. All in all, the current PPU brass is the best fit for the money.

You can also pull the SAAMI drawing off of the net. With a little bit of trigonometry in a spread sheet you will find that the SAAMI and CIP drawings are almost identical to within a few .0001 of an inch. How the British made chambers with so much variability I have no idea but it seems they do not have a decent drawing to guide the reamer grinders.
I have many hundreds of once fired .303 HXP cases and many of them seem to have been fired in rifles chambered by clowns - to the extent that there is a particular version that I call the clown chamber.

The small base Federal, WW and RP cases do serve a very good purpose though. The back end of a 6.5X53R Dutch M95 Mannlicher chamber measures .453 to .454 so the smaller American bases make excellent cases the Dutch rifles.

I think you are wrong about the dies starting out small and wearing to produce a larger case etc.
In American industry many companies often make a product at minimum material condition. If they make millions of the item they will save a gram or two per item.
So they will ship the lightest item that meets the drawing. That is standard practice with sheet aluminum.

Any base diameters from .452" to .460" are within SAAMI .303 specs. (.30/40 spec is .001" greater.) What size comes out on a specific production run simply depends on the finish production die's history. New die: small base - worn die: large base. Trying to predict what you'll find in the next batch you buy based on the kind of small sample most of us enthusiasts have available is an exercise in futility.

303carbine, CIP maximum cartridge base diameter (P1) for .303 British is 11.68mm. With a tolerance of -0.2mm giving 11.48mm minimum, your figures of 11.38 to 11.43mm seem low. Is it possible you aren't measuring immediately adjacent to the rim or your caliper needs calibration?

Attachment 64101

[Parashooter]

ireload2,
My question about measurement and calibration was directed to participant "303carbine", not you. Everything of yours I've read appears careful and well-reasoned. I don't doubt the accuracy of data you've presented at all.

[303carbine]

ireload2,
My question about measurement and calibration was directed to participant "303carbine", not you. Everything of yours I've read appears careful and well-reasoned. I don't doubt the accuracy of data you've presented at all.

My only point was that the Krag brass seems to last longer due to the measurement at the base, it is a bit bigger making the brass last longer for me anyways.
I have some 303 case drawings in front of me from the Hodgdon reloading book, the Krag brass measures 11.61 mm at the base, the 303 British measures 11.56 mm.
I didn't write the book by the way..........

[Bruce_in_Oz]

Well, I see it like this:

In British service, reloading ones cases was a non-event.

Hence, if the ammo went into the chamber and the "headspace" was within tolerances, everything was apples. Ammo went "BANG", brass sealed the breech, bullet went downrange; reload and repeat as required.

Furthermore, the reamers used to cut the chambers were traditionally not the fabulous products of Clymer, PT&G etc. but, barely recognizable "D" reamers for roughing and, just to make it interesting, the chambers were cut in "stages" and, the "finishing touch" was provided by firing a special "proof" cartridge that was supposed to "swell" the chamber/breech reinforce into the receiver body AND seat the bolt / body locking surfaces into final engagement. (That info is found in the various "Specification" documents floating about the place.)

Thus, in all likelihood, barrels cut at the beginning of the life of a "brand-new" reamer set would probably be a little "oversized", diameter-wise and possibly shoulder-length wise.

As the reamer set was used, it was periodically re-sharpened and thus reduced in diameter.

At some point, these tools would reach the end of their re-grinding lives and be replaced by a new, slightly oversized tools and the cycle would continue

As long as the assembled "headspace" was within tolerances and the chamber was not so oversized as to produce major splits and, most seriously, head separation, all was OK.

These are BATTLE rifles, not 1000 yd. bench-rest jobs.

I further suspect that the business of "mud clearance" in, especially WW1 chambers, is not all it seems. The Ross had a reputation for superb accuracy but significant difficulties in nasty conditions. The powers that be "opened up" the chambers, pretty much to no avail.

If you are shoveling mud into the chamber and locking surfaces of your rifle with every reload, there is something wrong with both the basic design and the matter of ammo handling.

The other beauty of the Lee-Enfield design is that, being rear-locking and only having TWO, fairly exposed, locking surfaces, it was MUCH easier to clear and get back into action than a badly slimed-up Mauser or, in particular, Ross.

My two-bob's worth.