Quote Originally Posted by Jon Budd View Post
Agree on sealing, I machine a taper to the end of the sleave, so that the outer edge is about 0.3mm further back than the inner edge.. the void is filled with loctite / bond and it ensures that the inside bore is really tight flush to the end of the comp tube. On a TX, where the endcap is remoaveable, I machine a recess around the outside of the face face such that the unmachined inner of the end cap protrudes slightly into the sleave (around 1mm), which makes for a really good seal.

As for your 21, just stick with 22 or 23, you have so much more scope for tuning... quite why it's short on power, no idea besides what you have suggested, but that won't stop me guessing
- surface finish of the bore holding lube or not (which provides a little power through combustion)
- pellet seat / fit in the breech affecting release pressure
- leaks around the tp and the end plug
My solution to sealing the sleeve is to fit a 1mm ccs o ring to the od of the sleeve, even then sometimes they don't seal , the real answer is a one piece end cap/ sleeve , but that's a lot of work, agree on the 22mm, but the 21mm shoots so nicely. today was checking the target gun down at the greyhound and put 12 shots touching strung out horizontally off the knee
just spotted Phil's post he does the one piece end cap/ sleeve