Winchester 220 Swift Brass

[RonAKA]

Just to close this out, the seller agreed that it was an inferior batch of brass. Turns out he had purchased a bunch from an estate sale and this was a part of it. No telling when it was made. He promptly refunded my money.

Besides the base diameter being out of spec, the base to shoulder dimensions were all over the place. The short ones are the ones that separated, understandably.

I discovered another bag of 100 that I bought from Midway. These all checked out well and should work fine.

I would reduce your normal maximum load a bit, and seat the bullet to a solid jam in the lands. That should keep your cartridge head on the bolt face on the first firing. When you reload, bump the shoulder only 0.001" and you should be fine.

 

[yotehater]

I agree mr gruffy is a bit hard to follow at times but his method of necking up short cases then resizing the neck is a very practical method. So many new cases are produced now on minimum SAAMI specs it is a common problem. I like to neck up then reduce just enough to create the false shoulder that the bolt has light resistance to closing. Jamming the bullet into the lands doesn't always work as neck tension determines how much resistance to moving in the chamber the case does before pressure expands the brass. YMMV