Mark,
"............So, I'm suspecting dieseling. I'm on about pellet 900 but the gun sounds loud and sort jumpy in my hand sometimes.
I've just put in my new trigger, but it was sending those flyers before from time to time. .............."
Sounds familar.
When I put in the gas ram, being it was a relativly new gun, I didn't bother to pull the piston out and check the seal while the gun was open. Once I got the scope mount issues delt with, it would group well for a few shots, but was still throwing about every third, or fourth shot. After over a hunded pellets since the gas ram install, it was still smoking a bit. Some shots more than others. Groups were coming out tending toward vertical stringing, so I suspected differances in velocity.
I started reading up on here about seal problems with Gamos. The more I read, the more it sounded like the seal was leaking. I ordered some new seals and when I opened it up, sure enough, the seal had a couple of chunks missing.
New seal is in and no more flyers, ...... except those I cause.
Paul.