Definitely good food for thought, and certainly tracks. I have no idea what the peak cylinder temp is on these things, but I imagine it's quite high, so temperature would essentially have to be a factor. And I guess similar to a piston engine with varying material types and expansion rates, as well as seal properties like elasticity, lubrication lubricity and viscosity. There could potentially be several factors that could have a complex relationship affecting compression or efficiency.I agree guns for hunting you need predictable cold shots. Unfortunately most springers aren't good at that. When you find one that is you treasure it. There's certain things that can be done to to minimize that. It's a long list. Sometimes it works sometimes it don't. It has alot to do with piston seal design and fit. Lubricant type and how its applied can make a difference as well. As Mike mentioned you'll find some pellets are more prone to needing warm up shots. typiclly tighter pellets do. Too loose is NG either. In your gun I've gotten the best power and performance out of FTTs, RWS hobbies and Superpoints. The last two fit looser but not too loose and are more likely to shoot true cold. I used the RWS pellets in my 22 Hw50 for squirrels and sparrows.
Here's something that happens that drove me nuts for a long time. Maybe its what's going on with you. I'll shoot my guns for sometimes hundreds of shots to get them sighted in perfectly, to get my best groups or to just have fun. After 25 or 30 shots velocities start to drop a tad and the poi will start to slide in any direction. I may follow the slide with the scope adjustments to stay on target as I shoot sometimes hundreds of shots in a session. By the end of the session the rifle is shooting markedly slower and the scope has been adjusted far from where it was when the gun was cold at the start of the session.
Now you put the gun a way everything goes cold and the scope is left adjusted to a warm gun from a long session. Now the first shot is faster and far off your POA. If you want the gun for hunting sight it in within the first 20 shots. If you want to shoot it for groups don't adjust the scope for that. Let the groups move around off target. it'll have no effect on their size.
If you want to shoot your POA (army men) for a long session. Mark your turrets where you were zeroed at the very beginning of the session and return them there before you put the gun away. Then your cold shot should be close.
There's reasons why the velocity drops and the POI wanders on long sessions that I haven't been able to fix yet. It's tied to compression heat and the thermal expansion of parts. Until I get my shop up I'll have to live with it. You'll find this situation gets acerbated by high ambient temps and bright sunlight. Your altitude may not help either.
Then there's a million reasons for a gun that wont group. Group size should remain fairly consistent early on. On hot sunny days groups will go bad on long session from thermal expansion.
maybe this helps. I hope so
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