I'm fully aware of that, I have several for my P-226 and other hi-cap handguns..
My point was that the range master had better make sure there are no hi-cap mags being used instead of ignoring the ban and letting his customers use them on his property. It's too easy to get busted by an undercover LEO posing as a customer.....
That’s true.
Or the undercover LEO could arrest the possessor on the spot.
Selective enforcement of the law is the easiest way to cow the peasants.