Gun advocates want to interpret the constitution as written by the founding fathers.
If you consider that in 1791, firearms were very simple and the founding fathers surely had no idea what guns would be like 200+ years from then, they might not have written the same amendment.
Therefor it makes sense to interpret the amendment as it was written at the time, in terms of technology.
Ban any automatic rifle/gun and anything that can do more damage. Guns are single-shot, loaded through muzzle, fired by flintlock.