I have a Mountain Stalker in .54 caliber. It is a fantastic roundball shooter. I shoot 80 grains of Triple Se7en 2f a wonder wad, and a patched roundball. The first year I got it the rifle tuned so fast that I took it out for a hunting try and ended up taking three deer with it and roundball. It drops them where they stood.

I did pick up a set of Star Dot fiber optic sights from Wal Mart and put them on the rifle in place of the factory ones since they are adjustable.

If the new nipple does not help, e-mail CVA and see what they have to say about it. Mine did that at first but I went to the new hot shot nipple and it stopped....