My experience with the 8mm is with an 8X60 RS, (in an old J.P. Sauer SxS double) but it is close enough to the 8X57JS to be able to tell you that these 8mm s are very effective rounds! I use the 200-grain Nosler Partition at 2620 FPS as an all-around load, and have used the Sierra 175 also. Both are good for game up to elk and black bear!!