[TigersEye]

What was the “violent crime?”
And where do you get a “31 round magazine?” I have never heard of a mag with that odd capacity.

[deks]

For Glock pistols there’s 33 round magazines available...

https://gunmagwarehouse.com/glock-gen-4-5-glock-17-19-26-34-9mm-33-round-factory-magazine.html

[jonascord]

Per the picture, the AR is a, perhaps, 9mm, with a staggered mag.

ARs can be built with a variety of uppers, in a vast selection of chamberings.