The widely -used by mass murderers in the US AR 15 rifle is the civilian — semi-automatic version of the US military’s basic standard rifle since Vietnam, the M16.
The M16 is made by Colt and Colt — owned companies, such as FN Manufacturing ...and they are NOT for sale to other than the US Government by Federal law...except for these, which are for sale online…
www.cnn.com/…
The M-16 was invented by Eugene Stoner, who invented and designed weapons for the US military — especially the Marines — since WWII…
en.wikipedia.org/…
I’m sure this is more than many of you want to know about these rifles, or guns in general...but it explains a lot...
I was in the Army in the late 1960’s and we trained on M16’s...they are very easy to shoot well, and they are easy to learn...and there are literally hundreds of “accessories” and parts for them readily available online...they are the first choice for potential mass killers because they were simply designed as efficient people-shooters and nothing else. FWIW, I don’t think even the AR15 semi auto rifles available now should be for sale to civilians. There really is no reason for this...