hi thanks for reply fv432. the problem is ive moved the pivot point of the gun to the mantel where it should be the standard unit dosnt have enougth travel now i need about 29 mm if it is fitted at the rear and there is not much room left anywhere else because of microswitches and servo to opperate the recoil plus cutting to give room for it to travel without hitting. I keep thinking of a servo mounted horizontaly with a cam of some discription with a peg to raise and lower but it has to move slowly and this where i need the advice how to make a servo move slow.Im a retired aircraft engineer not a eletromagician anything i cant see i dont understand i think the mechanics will work its the electrics do i put in resistors if so which ones or is it trial&error