hello everyone, I experienced something today and I don't really know if its common or not so I want to get your input on this. I tuned my avenger 22 cal to shoot the jsb 18 gr at 913 fps, when I tuned it I shot 4 or 5 dupes in a row at 913 and the rest of the shots were within I think 7 fps of that, pretty good tune and great accuracy. today, a few days after tuning, I noticed my groups were considerably larger than before, so I ran some shots over the chronograph and saw the velocity jumping between 825 fps and 907fps. is this something any of you have experienced? I retuned the gun for the jsb 25.4s at 880 fps so not a big deal in the end but does seem concerning nonetheless. I would love to not have to retune my gun every week 
. I should mention that the temp today was about 1 degrees F lower than when I tuned it, but I would think if anything I would loose a few fps, not widely inconsistent velocities. also, my reg was not creeping at all, and my hammer spring did not seem to move at all. I did max out the hammer spring (was not before) to see if I could get the velocity back at that reg setting (2k psi) and I was not, the velocity maxed out at about 880fps today with the 18gr down from the 913 prior. the gun is still new with probably about 200-300 shots thru it at most, that may even be a bit generous. thoughts?
. I should mention that the temp today was about 1 degrees F lower than when I tuned it, but I would think if anything I would loose a few fps, not widely inconsistent velocities. also, my reg was not creeping at all, and my hammer spring did not seem to move at all. I did max out the hammer spring (was not before) to see if I could get the velocity back at that reg setting (2k psi) and I was not, the velocity maxed out at about 880fps today with the 18gr down from the 913 prior. the gun is still new with probably about 200-300 shots thru it at most, that may even be a bit generous. thoughts?