My newest bullets from the RCBS 200 gr SWC TCBB mold showed a little leading at an average 1150-1160 some did show 1200 fps. It may have been that the lube was being blown past because I was driving them pretty hard and the bevel base may have led to this some what because the bullet's base didn't oburate to seal the back end enough fast enough. I may consider cutting out the bevel base to make them flat base bullets, that way the gases will act quicker to make it seal.
The bevel base helps with easier loading as they enter the case mouth. Another thing is too much crimp that can squeeze the bullet diameter down even smaller allowing the lube to blow by even easier!
NRA Life Member
BASS Life Member