Given how rarely (by comparison) AR-15s and similar rifles are used to kill people, I do not think such sufficient reason is given.
Let’s look at dead people per gun manufactured, by gun type.
I think that would be a very good idea. However, as with all gun death issues we need to separate suicide from homicide as they have very different driving forces and thus an average is not remotely representative.
....
Looking at homicides I find: Handguns: 6,368 for 2019 (the last year I'm seeing in the table I pulled up). Rifles: 364. Sales for Jan 2019 (reasonably representative, the table is per month): Handguns: 567,970. Long guns (which would include shotguns): 382,090. Since I'm stuck lumping in shotguns I'll go back and add in the 200 shotgun murders for 2019.
Thus for handguns I find 1.12%. Long guns, .148%
The deaths per gun are nearly 10x as high for handguns.
Looking at some ancient data on suicides likewise finds handguns disproportionately represented. (Which isn't a surprise given the difficulty of shooting yourself in a vital spot with a long-barreled weapon.)