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
The person who developed the HE system doesnt supply rams now .To encourage someone to fit the wrong ram to increase power over FAC levels is twatish to say the least .(1) its illegal (2) the