Re: Loads for the M4--16" carbine
The velocities will change a bit, but that's about all. Your 16" with a 1x7" will stabilize any bullet that a 20" 1x7" will, it'll just give you a bit less velocity for the same load. This is a function of expansion ratio, nothing more. The same powders that give good results in the longer barrels will also give good results in the 16". I'd be more inclined to go with RL-15, Varget or N140 over the H322 or H335 with the 75 grain bullets, but the two Hodgdon offerings would be great choices for anything from 50 to 62 grains or so. I have a couple of 16" guns, more 20" than I care to admit, and a couple 26" match rifles. They all get the same ammo, unless there's a twist issue (one of my 16" guns is a 1x9") to consider.