He's likely referring to the M4A1 Colt, which the US openly ships to Israel as recently as this year..

A lot of those rifles make their way to settlers' hands through various channels.

And machine gun is just vernacular for a fully automatic rifle.

Making it loudly known that you're ammosexual doesn't detract from the point the Congressman was making, which is that it's fucking ridiculous to have a bunch of plain clothes teenagers pointing weapons that the US gave them just for visiting a village that they decided to vandalize days prior.

Red dot vs laser sight, machine gun vs AR, silencer vs suppressor — who gives a shit about the right terminology? You understand perfectly what he's saying and what happened.