If you intend to hunt big game, the various Swedish Mausers in 6.5x55 are VERY mild in the recoil department...and EXTREMELY accurate.
In the same gun, though, with the same stock and same barrel length (the only difference being caliber), 7.62x39mm will produce about 70% more recoil than 5.56x45mm. The momentum of a 55gr .223 round at 3000 ft/sec is 3.26 kg-m/s, if I figure it right; the momentum of a 122gr 7.62x39mm at 2350 ft/sec is 5.66 kg-m/s, neglecting the momentum of the gases.Actually 7.62x39 isn't sharper. I have a Saiga .223 and a standard AK, as well as an SKS. The Saiga actually hurt a bit because of its short, sharp recoil, whereas the 7.62x39 round was more pleasant because it had a longer, more gentle recoil. The Saiga doesn't hurt anymore now that I converted it, though; the new stock has a spring plate on it.
I have a Romanian AK in 7.62x39mm with a metal sidefolder