How is this going to be enforced?

I shoot at the Golden Gun Club. Is the ACSO going to patrol the line and interrogate everyone who is using a 20 or 30 round PMAG? Is the asshole FUDD or fuckstain liberal next to you going to call the Sheriff b/c they don't like your EBR? How is the Sheriff going to handle this, you've got a hot rifle and you're target shooting, are they going to draw down on you and order you to comply? If you make a wrong move in their eyes are they going to light you up?

I think I'm going to be using USGI AR mags with no dates on them just to see what happens.