That's a good idea John .
Did some testing with the sliding nose piston today as it's easier to alter than the inertia weight idea .
Firstly I built it with a spacer instead of a buffer and set the power ( 11.4 fpe) to give a base line.
I then put two o rings in that were sized to just slide in the comp tube power went down by. 1 fpe ,increasing the pre load sent the power lower , I believe this meant the o rings were expanding too easily on the power stroke slowing it all down , it did soften the cycle, probably because the power was down.
Secondly I put two X rings in smaller in diameter and more rigid due to the square section, had the same result, so reasoned the pressure involved must be high enough to compress them too easily.
Thirdly made a spacer up and used a single o ring of a smaller diameter (actually a 20 mm stretched to fit ), and the power shot up, to 11.9 so a useful increase I reduced the pre load to bring it back to 11.4 .
There is a definite improvement to the cycle over the piston without the buffer in , not very scientific but I shoot it indoors over the chrono and have to use ear plugs normally, with this I don't need them .
So now need to shoot it alongside the other gun , weather is too bad today, but plan to bring both guns to the bash for my chief testers to have a go , should be interesting.
One downside is there is a larger shot to shot spread than I like, I think it's due to some movement between the nose and the piston body, so going to button the front to keep it all in line. Hopefully that will sort it out.