So the guys at Perry shooting rapid fire in the service rifle match using 7.62x51 M1As (one of the fastest cyclic rates around), do not crimp their SMKs ?
Not that many M1a's on the firing line anymore. They rapidly disappeared after the Army started winning in the mid 90's. The last the Marine Corp Team shot M14's XTC was in 1996, half the team had M14's, the other M16's.
Long range, heck if I know.
I don't know any Master Class or higher service rifle shooter who crimps their bullets. Might be some marksman, but since everyone copies what the big dogs do, they would get out of the habit.
In terms of cycle rates, a AR or M14 is nothing compared with things like MG42's.
This is one of my better prone rapid fire groups, at 100 yards, with a M1a. I have never crimped.