Registered machine guns owners have the reputation of being the most well behaved class of firearms owners for the last 90 years because of the tax and registration process involved as well as the cost to join the group.
Something that a lot of people fail to grasp is that in the majority of cases, it takes a little bit of time before you can join the legal, transferable machinegun owners club. Although as soon as you turn 21, you legally can, the vast majority of 21 year olds don't have the disposable income to buy in.
By the time most of us (who are not trust fund babies) have the cash available to buy transferables, we have matured enough as shooters to not behave at ranges like the majority of kids in their 20s do. The kind of behaviour that makes you pack up your stuff and move as far away from them as possible so you don't accidentally get shot by one as they laugh and spray the berms with uncontrolled hipfire.
Today, you can pick up a basic, low budget AR for under $500, and a FRT for what, $150? This is well within the budget of the average high school dropout. And these kids were bad enough when you encountered them at the range when they were shooting semi-auto. They are going to be intolerable doing mag dumps with their new FRTs in-between hits on the vape full of weed.
This behaviour will be noticed and soon enough it will be impossible to find a range that allows FA fire, specifically because of kids and their FRTs.
And the states will not differentiate between "real" registered MGs and FRTs. They will lump them in together because the state level lawmakers and lawyers don't know the difference, nor do they care. So the kids and their "loophole" devices are most certainly going to not only give "real" MG owners a bad reputation, but they are going to bring down a lot of bans on us too.
Guaranteed.
And that whole "common use" argument is as useless and the stack of law cases that "sovereign citizens" try to use to get out of traffic violations.