i think he means a theoben gas strutt it replaces the spring the added advantage apart from power is that there is little recoil and if you buy the the same calibre strutt it will be on the limit but if you have a .22 and put a 177 strutt in the ,power is about 18ft lb theoben used to do one for the hw i think its def worth doing if you need the extra poke you can mail order them out of air gunner mag
tanks bull would like to reduce the recoil & take it over legal limitt i have a application form for a facdo i apply for the licence first? & how much ftlb can it go up to? at the mome