- Sorry for my ignorance, but is a semi-auto M4 still an AR15? If no, what is it called?
Technically, if it isn't a Colt, it isn't an AR-15. They hold the trademark for that.
Other rifles will usually have a similar nom de guerre like XM-15 or M-15 or something.
Although AR-15 has become pretty much the terminology covering all of them.
M4 is the military designation for the 14.5" bbl select fire model that Colt produces.
You can get Colt's marked with M4 now. They lost a trademark lawsuit against Bushmaster several years ago and anyone can techincally call their rifle a M4, but I don't know anyone that does off the top of my head.
Colloquially the semi-auto only copies of the M4 that civilians can purchase are called M4geries.
Bravo Company has a reputation as the go to place for custom hard use weapons. There are lots of other companies out there and even more companies that are selling "accessories".