OMG
it sounds like if I have a "tight" Delrin spring guide. I might be loosing power still with warmer weather ...with my Tony Leach set up?
Gawd...damn. Now I'll need to somehow obtain a metallic spring guide. Looks like more tinkering/shopping and less shooting in my future.
Hey, you will probably be ok ….do not panic.
The critical area thrown up here is when we have super close tolerances for the piston bearings.
Tony tried to build in very high quality to his limits and fits, in an effort to remove even the smallest amounts of slop from the piston running in the chamber. He should be commended for his effort, but you just cannot do this with Delrin….because you must allow for 0.15mm to 0.2mm of thermal expansion.
So….If working with minimal 0.1mm clearances, you have a significant chance of a piston ending up with an interference fit with Delrin.
However, your spring guide is not nearly so critical, especially if not made tight in the first place.
Maybe +-10 fps rise and fall from this component…but obviously if running a Tinbum type guide thats a good shove fit, you are going to get issues with temp variation.
I noticed many shooters who would set there rifles up shooting ragged one holers all day long, then the following day their zero had shifted. It is their Delrin components reacting to varying temperatures.
Its interesting that the FWB 300 match series of rifles and the FWB 65/80 pistols would hold zero every day, regardless of temp, never shifting zero as they ran steel piston rings on steel chambers…Any slight thermal expansion would be uniform to the 2 components, but steel hardly suffering in respect of thermal expansion (0.02) when compared to Acetals and Nylons. (0.1 to 0.2mm)
Ive had a long held opinion that OEM manufactured guns….Air Arms/ HW etc may well shoot with more damped cycles when switching to Delrin kits, telling the shooter this has to be better but IMO not nearly so thermally consistent day to day. The shooter then left puzzled and asking questions. Is it lube, pellets, me etc….
Its all over the forums that this happens for no apparent reason.
Its tight tolerance Delrin components ..sometimes Moly thickening …often both.