I use an RCBS 2die set with Lee factory crimp die. The rcbs comes with a smaller (for .308) and larger ( for .311-.312) expander balls. I recently did a test loading .311 bullets in brass sized for 308 and brass sized for .311. Same powder charges and seating depth, long story short, they both shot the same. Same point of impact same group size. My rifle does shoot better with a light crimp though.


JTD