Float Pilot
Member
it was made to fight our enemies. It was not made just to fight the NVA. If that was all it was made for we would have switched back to the M14 or made something else already.
The AR-10 (mid 1950s) was designed as an all- around rifle. The 22 caliber, high velocity stuff as a secondary project was worked on by a couple other folks besides Stoner... However the initial few years field use first by the Air Force and then the Army was in South East Asia. Remember that it was non-infantry guys like Lemay (AF) and that goof ball Sec Def McaNamara who pushed it through. The Regular Army was not crazy about it..
How it worked or did not work there (S.E.A.) , led to changes in ammo, twist rate, fire doctrine and all sorts of other ideas on war-fighting.
Had conditions been different during that 10 year period, the M16 and 5.56mm may have well been superseded or modified before they sank more money into it...
One of the first things they taught us in command school was that the USA has the tendency to prepare, train and supply with the last war in mind.
The bullet is not overstabilized in 1:7 twist unless you use too light of a round. Then, the spin literally tears it apart. But for 55-~80 grains, 1:7 is ideal.
No it is not ideal for the 62grain bullet. They went to the 1 in 7 twist so it would stabilize the much longer tracer round that was developed for the SAW. It is bullet length, not weight, which determines the needed twist rate. Even 45 grain bullets of modern construction hold together just fine in the 1 in 7 twist.
Your number-one choice is basically destroying what range the M4 has by now possibly understabilizing the bullet.
My comment was for urban fighting, building interiors etc. The stuff that sub-guns and shotguns were really made to do...
A 1 in 9 twist stabilizes 62 grain M-855 just fine. Even at reduced velocity from a 11.5 inch barrel. We tested it at 400 meters and there was no impact yawing.
In fact it allows slightly more velocity to be produced since it reduces friction. The twist rate would have to be played with to strike a balance. For urban fighting at ranges out to 300 meters , a marginally stabilized bullet will tumble (often) when entering a body. A fast spinning round , at the reduced velocities caused by the 14.5 inch barrel, tends to poke a hole more often than not.
Of course an impact velocity of 2,500 to 2,600 is preferred for any sort of massive trauma from a small bullet. The short M4 hampers that considerably.