AS STATED PREVIOUSLY,
the US had a large magazine ban about 20 years ago. The law expired due to a sunset provision, but the research after showed it had ABSOLUTELY NO EFFECT.
1) very few crimes are committed with rifles of any kind so they are a statistical null.
Note here that something like a MAC-10 or UZI is classified as a handgun, not a rifle, because of their short length.
2) anyone wanting a larger capacity can easily tape 2 mags together and RAPIDLY flip them when one runs out. We're talking a second or so with practice.
3) if they're REALLY dedicated minor sheet metal (or in some cases, plastic) work can make or extend a mag.
Magazines are basically just an elongated box with a ~20 guage piano wire spring inside. The follower (bullet pusher) can be made of shaped plastic, brass or even dense wood. Anyone with high school shop skills can make one. Instructions are online.