i'm obviously not a rifle guy, but i picked up a hkm770, and a friend of mine who was an engineer in the forces, told me to get 7,62 x 39 it will work and is cheap...so i did, obviously, our military doesn't train that well in mil cals; and i appreciate all the comments about my mistake...i'll bet i'm not the first and won't be the last to make it, i knew the error as soon as i opened the crates. to use up my useless ammo i'm ordering a robinson arms xcr in 7.62 x 39...is that a good choice or am i jumping the "gun" again? .... please hold your jeers i'm a newb in this category and am not really feeling that welcome in it... but if you'd like to discuss vintage Am. side by sides or english shotguns that's more my thing.