Anyone know how much recoil force the M14 generates with standard loads?
Could look up a figure in foot-lbs of recoil energy, or foot-seconds (not even sure if that's the right unit of measurement!) of impulse, but there's no point bothering with that, because it's quite unrelated to what you probably really want to know: how pleasant/unpleasant is the rifle to shoot?
It's unusual that a rifle hurts you just because it is powerful; it's much more common that a poor fit (to you, as an individual) is what is really causing the pain (e.g. a trigger guard pinching a finger, a cheekpiece whacking your face, or a poorly fitting butt digging into your shoulder). One of the nastiest, most painful rifles I've ever shot is a lever action Marlin in .32 Special (!!!), because it was whacking me in the cheek bone quite severely. I've fired a good .375 H&H, that was more pleasant than most ordinary hunting rifles; and a bolt action .50 BMG that was monstrously, impressively powerful, but actually more comfortable to shoot than most 12 gauge shotguns I've fired.
I have found an M-14 to be a remarkably, unusually pleasant .308 rifle to fire. Its cycling action somehow seems to actually soak up and spread the recoil in a useful manner; gun writers talk about this being a feature of semiautos, but an M-14 is the only semi I've ever fired in which I've noticed, "hey, this is nice!". And yet my Garand somehow seems much harsher, frequently poking my thumb into my nose; and a .303 Lee-Enfield, or an FN-FAL are far more brutish, at least to me.
I find an M-14 to be much more comfortable to shoot than a .308 bolt action rifle of hunting weight (some of those can be mighty sharp!), and even many of target rifle weight (~14#). And, the one time I got to shoot a full-auto M-14, it was completely pleasant and enjoyable to shoot (but totally uncontrollable, confirming at least for me all the things you read about it and the FN, and why in practice they were only used as semiautos; I couldn't hold it on a fridge at ~15 yards).