Not saying that a loose stock is the problem, but if you're using the Crosman skeleton stock (1399?) it could be.I had one for a short time on my 2400kt and needed to shim the stock against the grip frame to take most of the wobble out. I never noticed a problem (other than a loose feeling), but I never rested the butt against anything other than my shoulder when shooting from a bench.
My groups suffer from the loose nut BEHIND the stock. Seriously, ANY looseness anywhere is a bad thing.Shot to shot consistency goes right out the window.Cheers,Smoketown