The bullets that I have been playing with for the MR, are Hornady 500/300 gr FTX and the Barnes 500/275 XPB both are hand gun bullets. You knurl them up to fit your barrel (some need more and some need less) depends on your barrel, I like to use a felt wad between the powder and the bullet to help seal the gases,(there are sub bases by MMP also but have not tried them), There is some great info about it on this forum about it, check out sabotless shooting.