I'm using a XS system ghost ring on my Parker Hale which has been re-reamed to .458 Lott. It works just fine for abusing the 8" and 10" steel plates at our 100 yd. range. I normally shoot a 500 gr Woodliegh soft at around 2,200 fps and had to use the taller ghost ring which mounts on a Weaver base on the rear reciever bridge