Paul.
Like yours, my Gamo scope went early on.
I had already replaced the Gamo trigger with a Tuna trigger. As you know, it makes a world of differance, but gun still wouldn't group consistantly. Figured the gun is still breaking in, and so am I to it.
I replaced the scope with a Leapers mini swat, and an Accushot one-piece mount which made an improvment, but not for long. After a short while it would'nt group consistantly.
I put a gas ram in and didn't check the seal. I assumed that since it was a fairly new gun, the seal was good. In a short time, groups still went back to being inconsistant.
Found the Leapers one-piece mount had a broken stop pin. Made a stronger one, but again, in a short order, the gun went back to being inconsistant.
Finally checked the seal and found a couple of chunks gone from the lip. Replaced the seal with a Maccari, de-burred all inside, gave it a good cleaning, plus used his lube kit, and it's been fine since.
The gun smoked since day one, and while it smoked less with more use, it never realy stopped until after I put the new seal in. Sometimes a bit more smoke than other shots. This being my first springer, I had no idea what to expect and how long it would take to 'break-in', so I didn't pay much attention to what the smoke meant. The factory seal was probably going all the while that I was eliminating other problems.
Now, it's fun to shoot.
Paul.