Out of interest, how can you tell?
Mainly because machine guns and destructive devices are effectively banned for sale to the public in the U.S so it’s unlikely to start with . Anyway it’s an Extar 556 which is semi auto.
(I know very little about guns – but it looks like something I’d expect to be firing full auto in a movie or game)
This is actually quite a big part of the debate in the U.S at present. Pro gun control lobby want to ban “assault rifles” because they imagine this
but that’s a machine gun. And already banned. So they’re referring to semi automatic guns that look like machine guns. So they end up alienating the moderate middle ground, gun owners who are pro gun control, and make themselves a laughing stock among the hardcore NRA 2nd amendment types. Imagine a local newspaper running a story about banning mountain bikes and picturing a motox bike.