Good advise! Glad I read this. I had a Crosman Nitro Venom Dusk.22 with the first edition gas piston, not the NP2. It did the same thing soon after warranty ran out. Would not group any more,one shot sounded different from another.Got rid of it. Thought I might give the NP2 a second chance. Not after reading this. Crosman is becoming disappointing even with their pellets. I have a Hatsan with their gas piston and have had no problems so far and might give Gamo's inert gas technology a try in one of theirs., but done with the Crosman's version.