The "R" in NRA
The Article refers to the "R" standing for hunting rifle, not so much, the men who formed the NRA in 1871, did it for marksmanship training, as they felt they had seen dismal performance during the Civil War. The Training involved around training of military type weapons of the era.
Just like everything else weapons have envolved, but now we are limited to civilian semi autos that happen to look like military weapons
H/T to Uncle