the extra space taken by washers and bearings the spring may become coil bound and need shortened.
Don't see how you can do that. My spring coils are only 3.3mm in diameter and the last coil is tapered down to 1.5mm so that it fits flat against the washer in the spring guide.
Folks,I see a few remedies to reduce vibration related noises from springer airguns. One such remedy is to polish the spring ends so that the spring can "wind up" smoothly on cocking (and presumably unwind on discharge).It occurred to me that if enabling the spring to rotate freely is a plus, then why not install a thrust bearing on the back end of the main spring? I am not sure there would be an advantage to bearings at both ends of the spring. Also, I have some concerns about the needle rollers falling out under certain conditions, if the bearing were forced to move along inside the piston head. So, just one thrust bearing at the tail end of the spring should do...As you can see from the links below, these bearings are very compact and not expensive. You would also select a matching hardened flat ground thrust washer for the needle rollers to run against:Bearing: www.mcmaster.com/5909k33 Washer: www.mcmaster.com/5909k46 To browse more bearing sizes, click here: https://www.mcmaster.com/thrust-washersNow, getting back to calming springer buzz; if a tight fitting spring guide helps damp that out, then perhaps allowing the spring to rotate free would actually allow more buzz because rotation would be undamped. On the other hand, if the spring coils rub on the guide in linear front to back motion, then they are also rubbing rotationally; thus providing freedom to turn, but in a damped manner. Thoughts about, or experience with this would be appreciated.
Two bronze washers with Moly grease between them, on the other hand, has been used successfully....
Solve your problem with a gas ram. No buzz no torque and I think no piston bounce or at least very little. I certainly can't feel anything like piston bounce. But there are some downsides and the cycle feels different. A steel spring is still good.I note in the thread about pressure at the end of the stroke a note that says a gas ram of equal energy has more piston bounce. I certainly can't feel it when shooting and it feels as if there is much less. Maybe it is just because there is no spring to thrash about.
This was discussed a while back on the old Yellow. Final conclusion, roller bearings have been known to come apart with disastrous results. Early attempts to reduce spring twist used polished washers.