Thread: Fireform markings

Your sectioned case looks fine to me. I have exactly the same marks on .257 and .280 cases when fire-forming to AI and have sectioned cases like you. Having confirmed they are OK, I've gone on to use them without any problems. Just my experience. Good idea to do as you have done and err on the side of caution. and the usual disclaimers when discussing any reloading activity apply.

The marks on my improved cases at the original shoulder line following fire-forming often look to be a problem - quite bright and crystalline looking, with an appearance like the brass will let go on the next firing - but I have trusted to the adequate annealing of the parent cases and AI-forming isn't asking that much of brass, sectioned a couple to confirm adequate thickness, and sure enough the brass has subsequently been fine. Failure has never occurred at that point.

I also get the distinct line above the web on both the 257AI and the 280AI from both the chamber on expansion and sizing dies on re-forming at the lowest point on the wall where contact occurs as in earlier posts. Quite useful as the position of this seems to be a good indicator as to how sloppy the chamber is cut, and then to some extent can then also be used as an indicator of peak pressure on firing, and also then how much the brass is being re-worked on body sizing. Thinning at this point on my cases produces a definite hollow on the inside of the wall opposite this ring. Case failures when they have occurred have been at this point (or neck splits) but only from repeated firing -forming cycles, the progression of the thinning can be tracked by feeling inside the cases. The mark alone is not in itself an issue IMO.