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I've been there and done that!
I, too, have an Arisaka T38. And when I first tried it out with some ferociously expensive Norma ammo the cases and primers looked just like yours.
Don't panic!
Don't go crazy looking for a headspace gauge!
Stay calm and read what follows right through before switching off in disgust, as I may be about to tread on a few toes. For which I apologize in advance, but it is all my considered opinion, based on not inconsiderable experience.
First, dear brethren across the pond, I have a couple of secrets to impart.
Many of our beloved old service rifles were designed and manufactured long before WWI. Long before CIP and SAAMI were thought up. The published specifications for several chamberings were, I suspect, derived long after said rifles were produced. A case of being wise after the event, but of course intended to provide help for commercial manufacturers. No imperial Japanese/Russian/British arsenal would have cared a hoot about international standards bodies.
Another secret: rifles, when you remove the military aura, are machines. Machines subjected to heavy loading and thus wear. So those chambers, which were never built according to CIP anyway, are now even bigger than when they were new. And when they were new, they were often built generously, so that the average Poilu or Tommy could drop his rounds in the mud, pick them up, wipe them on his grubby battledress, stick them in the chamber - and the rifle would still function properly. If you take some time to study the history of the Ross rifle, you will find that its lack of “muck tolerance” was a major cause of its failure on the battlefield – although it acquired a good reputation as a target rifle.
So “real world” imperial rifles were designed primarily to work reliably in conditions that would make a collector cringe. It is illuminating to read the descriptions of the trials that lead to the selection of the Martin-Henry as the British standard rifle in the 1860s, which involved soaking the rifles, burying them for weeks in the mud, digging them up, scraping out the muck, and firing them again. What passed such tests was a tough design - the M-H. Maybe not the target-shooter’s choice, or a watchmaker's showpiece. But very, very tough.
And, of course, it was not a typical military objective to reload cartridge cases. Except. of course, in the special case of Lettow-Vorbeck’s askaris in Tanganika. But that is another story…
Returning to our mutual problem: The T38 (I cannot speak for all, just mine, and maybe yours) has a chamber that is, particularly on a worn example, so much longer than the CIP figure, that when you load a case that has been fully sized to CIP specification the following occurs:
Note—I am indebted to jmoore for the first comprehensible description I ever read of this complex chain of events. Jmoore, if you are reading this, please chip in as I know you have done a lot of “T38”-thinking.
When the rifle is fired, the firing pin pushes the cartridge as far forwards as it can. If you remove the extractor, this could be so far forwards until the shoulder stops in the chamber that the firing pin is unable to detonate the primer. However, in most cases the extractor will hold the case well enough for the pin to detonate the primer. In your case, it looks as if the firing pin only just managed to cause detonation.
The case expands, and being thinner at the neck end, will grip the wall of the chamber there and start to push the rest of the case backwards, stretching it in the process. While this happens, the already ignited primer is pushed back out of the primer pocket much faster than the base of the case can move - the primer backs out and is forced flat onto the bolt face. The pressure causes the backed out portion of the primer cup to expand.
Now the base moves back as the case stretches. The primer cup, now slightly oversized, has the cartridge base forced down around it, flattening the cup, and this causes the cup to appear as in your photos.
I also had this effect, and thought "OMG, hazardous overpressure!" Not so, the cause is the enormous end play created by a modern cartridge made to CIP or SAAMI dimensions being fired in a chamber that is considerably longer to the shoulder. And the answer to this problem is to get the case to stretch at the neck and not at the base.
One solution has been thought out and described by jmoore, so at this point I defer to him. (You should be able to find it on this forum).
Since I already had a stock of the Norma ammo, I tried another solution. I simply used a bullet puller to pull the bullets out so far that when the cartridges were loaded the bullets touched the lands. When fired, the primers looked somewhat healthier, but still doubtful - probably because the neck tension was weakened by the partial pulling of the bullets.
So my next test will involve pulling the bullet completely, resizing the neck, and seating the bullet almost on the lands again, but with a slight crimp. I will report back when I have tried this out. In the meantime, the jmoore solution is best.
:wave:
Patrick
