So I’ve been doing some reading and watching some videos and unfortunately the rest of the world does all their testing with copper jacket bullets. So for cast I am wondering if I am using a .310” projectile for my 300AAC should I be using a .310” expander during the sizing process? With a .310” sizer ball the neck should spring back to .308-.309”. My current sizing die has an expander that measures .3067”.
Also currently for my brass I use a 30 Luger expander die to flare the brass and dump the powder. I haven’t seen any accuracy gain or loss from using it but I’m trying to tighten my groups up from the 3” average I’m getting at 100 yards.