both guns can kill and kill effectively on any game from deer to moose and elk size. both are flat shooters. both have tremendous speeds. and both offer alot of power. this is a good toss-up. but, when it comes down to it, you can examine the differences by the bullet's diameter and the old equations for sectional density. bullet weight as to bullet diameter. which basically determines whatsize of wound a bullet that size would leave in theparticular game you are hunting. wich also deterimes the "bleed wound" or how much faster the animal (COULD) bleed out if a larger would was put in the animal.looking at it from this aspect, i would recomend the 300 win mag. especially if you are thinking elk and moose. but , i have also read articles on plenty of hunters using 7mm.s for elk and larger and the outcome is the same( a dead elk). there is only few differences in ballistics. but most differences are just seen in bullet diameter and bullet weight offered in these calibers. both are effective.