I've been trying them out in my CVA hunter bolt, 50 cal. The barrel has a 1 in 32 twist, I wish it were at least 1 in 48 but 1:32 is what it is. I've fired about 20 shots and am grouping about 4in at 50 yards...not great but I haven't gotten dialed in to the charge the gun likes with this bullet yet. I think I can get good groups from the ball-et's if I find the right powder charge. Problem could just be my shooting right now, I've been shooting revolver more than rifle this year so I'm a bit out of practice with the long gun.
This gun likes the lead powerbelts and 100gr of pyrodex RS, but the powerbelts are expensive for targets and this gun doesn't quite have the twist I need for round ball.