Over the past couple of days, I've loaded up about 150 rounds of .243 ammo, for two different rifles. Basically all for load testing. The rifles require different seating depths, so, it's all been done in two lots. 3 different bullets: Hornady Vmax 65, Nosler BT 70, and Speer 85 SP. Apart from a bit of fiddling, to make sure I had the right seating depth for the right gun, it was mostly plain sailing.
Except for one thing. All of the cases are Winchester. They're sorted by weight, and are generally kept to a specific rifle and only neck sized. In this case though, all have been FL sized. Most are normal brass, but I have about 40 of the 'silver' cases. These have been used before, and seemed quite normal. But, this time, there was quite a bit more pressure involved in seating the bullet. Not for all, just a few. The act of seating actually removed a thin layer of metal from the surface of the projectile.

I pulled the bullets, and measured them and the cases, but they have exactly the same internal and external measurements as all the others. Even after running them through a die again (neck), they are still too 'tight'. As they start with the same internal width as all of the others, I guess this is an indication of a loss of elasticity. There are no signs of any 'nasties' on the cases. For the time being, I've put all of the silver cases aside.

Oh, the bullets were the Noslers, but I measured them as well and all was correct.

Any ideas, as I'm certainly bemused.

Do you chamfer your case mouths?

Have you trimmed the cases?

John Bartels __

Correct me if I'm wrong, but I'm assumimg that your bullet "shaving" occurs only with the "silver" cases. I'm also assuming the the "silver" is our common electroless nickel plating. This type of plating, though quite thin, as-deposited, is very strong, hard, and brittle. Much more so than the substrate brass. Hence, you are correct in gathering that the cases in question are less "elastic". Hence, it takes more force to expand the neck when seating the bullet. It also means that the "grip" of the neck on the seated bullet is also greater; thus an influence on internal ballistics. You are being prudent in using those cases separately.

In a practical sense, the cases are perfectly usable. However, "shaving" can be prevented by following the advice (belling and chamfering) posted above.

Good shooting.

Robert

John

I had the same thing on my 22-250 nickel plated case I had to put a heavy chamfer on the mouth of the case the first time I reload them after that they work fine

Thanks for the comments guys. I've just gone out and attacked them with the trimmer and chamfering tool. I'll keep them separate and see how they fare.