i have an s400 with a rowan mag conversion and its absolutley spot on, i wouldnt part with it,i also have a bsa scorpion (both in 177) the scorpion is very very accurate but for me theres no comparison the aa s400 wins hands down,shoots pellet on pellet every time,is as smooth as i could ask for,but as said its down to what fits you better, my bsa is for my son to use but i can use it quite comfortabley but again the aa fits me even better cheers