Mine's a .17AH. I've only shot 20's and 23's at about 3650 and never had a chuck do anything but die. Lots and lots of them. These are rockchucks and they're whatever size happens to be out there. They do get big. But this is also out to about 150yds. Rifle is a T/C 20" carbine truck gun with a 10 twist barrel, haven't tried 25's to see if they'll work with that twist.