I bought some xpb bullets for my 357 mag and e-mailed barnes for data....they responded that they didn't have any...it was still under development. I couldn't believe it. The bullet is on the market and they didn't test it???? All I can say is they are long for wt and you should download them (probably to starting loads of cup and core) and work up. Just what you want to hear with bullets that are almost $1.00 ea!