Dies sizing my .357 boolits down to .352 - .355

[Gunslinger]

I found my leading issue with the 9mm to be caused by my Dillon sizing die. After removing a boolit, it measured a surprising .352!! I had noticed the hour-glass shape of the cartridges, but didn't think it was this bad.

I borrowed a Hornady sizing die from a friend. A pulled boolit revealed a measurement of .355. Still too small... and still causing leading. I shoot 130gr wheel weights at 1020fps. I know this is what's causing my leading, as I have changed and adjusted everything else. I shoot a EAA Witness with a polygonal barrel slugged at .356.

Does anyone else have/had the same issue?! Can the die be reamed or anything to size the brass a little bigger?

I only use as much crimp as needed for the cartridge to fall in and out of the chamber by itself.

[RobS]

Here is a thread that I posted up detailing the brass sizing die swaging down on the boolit (post #13 & #15):

http://castboolits.gunloads.com/showthread.php?t=120655

And yes, sizing dies these days are designed for jecketed bullets. Another question, have you slugged your barrel to know what the groove diameter is?

[462]

Don't overlook the expander and/or the seating die, as the source of your boolit swaging problem. Die modification is often required to keep a boolit at its desired diameter.

For what it's worth, I've found Lyman dies to be the most boolit friendly.