had a quick look at Gerards post and will re read it and try to understand it later.
What I would like to try is something a lot simpler, that somebody with a lathe could knock up pretty quickly and could be reversed if needed. If a Tempest piston was drilled and tapped, it could always have the earlier Premier washer fitted if the gun needed to be taken back to the original stroke.
As I said in the earlier post, just a basic thing---shorter mainspring,polished trigger, a small top hat for the mainspring and a longer piston head/washer.
I prefer shooting .22 but for the "TARGET TEMPEST" I suppose it would have to be in .177.
Having read Gerards post again, it seems this would be easier to do with an earlier pistol, as a new cylinder end plug could be made up that was slightly longer and bored out to take a weight.A small spring could be put behind this weight to stop it flapping about. guessing a plug about 5/8 to 3/4 longer would do it.
He is a bit about Tempest?Hurricane trigger fettling. Refer to these pics http://www.airgunspares.com/store/pr...-Trigger-Wide/
and http://www.airgunspares.com/store/pr...t-Pistol-Sear/
I use 320 and 400 grit wet and dry paper to do them and they seem ok. With the sear, I polish both sides of the rounded bits on top, even though, the piston should not really touch them. I polish and try to take the angle back a touch more, the angled side of the cut out on the right of the picture. On the long leg I go the front face,the underside and the angled bit where it joins the back. (MORE ON THIS IN A BIT). On the trigger I do the flat face above the arc of the trigger blade, the face behind it and reduce the BUMP between that and the bit going up to the pin hole. This BUMP and the back bit of the leg of the sear are what "pauses" the trigger pull before releasing the piston. If you do a little work on the sear and the trigger, you can hold them in your fingers and rub one against another to get a good idea of this.Even with the BUMP on the trigger taken down a bit,I find slightly rounding the back edge of the sear helps. DO NOT GO MAD DOING THIS! Remember you can always have another go, but you cannot replace material.
So a bump for a donor piston or rough/cheap .177 Tempest?