In a way its simple but in a way it isn't. Its easy for me to understan the equal and opposite reaction part and the part bullet weight plays on it. On the other hand FELT recoil is another question. Why do some guns who 's recoil on paper is less,hurt the shoulder more than those with less on paper recoil? I am sure its weight of the gun, shape of the stock, the kind of recoil pad and so fourth. Strange to me is the fact tha I have shot many many rifles, some bigger by far than the 7MM Rem Mag. However the 7MM Mags seam to hit my shoulder harder than the 300 and 338 Mags. Is it recoil speed? It part of it in my head? Whatever it is it hurts.[:@]My 416 Rem mag is the only gun I have owned that hit me much harder than the 7 Mag.