I had a savage m10 re-barreled to 338 whisper a little while ago. Since 300 grain match bullets are not cheap, I decided to experiment with cast. I use an NEI mold to make 300 grain bullets from wheel weights. They come out of the mold at .340". The barrel throat is a bit tight I think. While it would let me chamber a jacketed bullet seated to touch the lands, the slightly wider cast bullet would not chamber unless I seated it down to where the crimping groove was just above the case mouth.

Sizing the bullets brought them down to .338", but I still have a hard time chambering a dummy round seated out to touch the lands. Using some graphite on the dummy round, I saw a mark on only one side of the bullet after extracting it. This is leading me to believe I have lots of runout after seating the bullet into the case. I am not set up to measure runout now. I will be trying gas checks after they arrive in the mail. The dies have a floating sleeve to align the case and bullet prior to pressing it into the case. Any suggestions? Thanks.

Ranb

Your problem might not be seating die runout. The mark on the boolit could be because of bolt closure ramping being a little off. But, that bolt closing problem is OK after the bolt is totally closed and locked, assuming everything is really concentric just before the shot. How deep is the gouge in the boolit? Should only be a scrape, rather than something that will catch your fingernail. ... felix

The only thing that I could add is something you may already do. And that is to seat the bullet in three or so stages spinning the cartridge 1/3 way as you go and see if that makes any difference. BM

Bill