Discovery accuracy

My first two Discovery's were very accurate. But, they both developed leaks while under warranty. Sent them back to Crosman. My third Discovery could hardly hit the side of a barn from the inside out. Well, really 1 1/2" to 2" at 25 yards.
Could see what looked like a tool mark close to the muzzle, but could not pin down how far back it was. I recrowned the barrel, no help. Recrowned it again, no help. Cut off 1/6", recrowned again, no help. Cut off another 1/8", recrowned again, no help. Cut off another 1/2" and recrowned. Hit the jackpot. Now, its shooting JSB RS pellets .22 cal. at 25 yards with group of 1/4" and another of 3/8".

Of course now, my TKO won't fit on the barrel because not enough clearance between barrel and air tube. Oh well, I have a P-rod and a M-rod that are silent so I can shoot anywhere I desire. I live in the country, so really I can shoot the Discovery even though it makes a lot of noise.

My son has a Discovery that has always been accurate. He wants a .25 cal. gun so wants to sell his Discovery. I was about ready to buy his and get rid of mine, but now I'll keep mine.