OzFclass

HI all, does anyone have any issues with consistent shoulder bump on starline brass? I anneal every time, use a whidden die without the decapping pin and mandrel. I get anything from 0 bump up to 5 thou and I cant pick up why. I even go as far as trying to be consistent with the press stroke. there is no movement in the press or die to allow a variance so teh only thing I can think of is the brass is inconsistent in some way.

Have you measured the shoulder before bump? Any difference there?

yes I have, there is really only 2 thou variation at the most from a fired case.

Has the brass been batched together throughout its life? Even with annealing, the history of brass seems to have some effect on its springback when bumping.

AlanF wrote:Has the brass been batched together throughout its life? Even with annealing, the history of brass seems to have some effect affect on its springback when bumping.

There is 2 batches in there that I havent kept seperated. Thats a possibility I didnt consider

how do you partially anneal?
getting that consistent is critical.
consistent lubing can help.
leaving the case in the die for a short period the same each time can also help.
0.005" variation is a bit of a worry.
bruce.

I have experienced the same problem with other brands of brass and have found the only way of overcoming the problem is to make the bottom of the FLS die make hard contact with the shellholder. All of my FLS dies (4 of them) size 10 thou shorter than a Go gauge length, so I have to use a +10 Redding competition shellholder to get 0 headspace. I haven't got an explanation why the variation occurs but I have found a fix (being make hard contact) for the problem of variation of the sizing length in my circumstances.
Philip

Leaving the case in the die for a consistent count each time I have found makes a big difference, but it sounds like inconsistent hardness to me