I don't think it makes much difference in practical terms.
In a 14.5-inch twist M16A1 carbine barrel you still got at least one full twist before the round leaves the muzzle. I've shot tens of thousands of M193 and commercial 55-grain rounds out of 1-7 twist 14.5 carbines as well as the old 1-12 twist M16A1 carbine.
I shot out at least one 1-9 twist carbine (I don't remember the brand) with M193 and commercial 55s.
Bookmarks