"substance abuse" would need to be clearly defined. Right now weed heads are not legally allowed to purchase a gun from a licensed dealer because weed is still illegal at the federal level and its the feds that approve or deny your ability to buy a gun. Weed heads lie on that part of the form so they can buy, but if something happens, you end up like this woman:
The mother of the 6-year-old boy accused of shooting his first grade teacher in Newport News, Virginia, was sentenced to 21 months in prison on federal charges.
abcnews.go.com
She got a deal, 'cause it's supposed to be 10 years of fed time, but being a weed head, even casually, can get you fed time for lying on the 4473.
I don't know about anywhere else, but out here to get a concealed pistol license, you need to go through a training class with also includes range time and it has to be renewed with a refresher course and range time every 5 years. That
could be extended to include long guns just on GP, but the hunting community out here would push back very hard against it. You already have to renew your hunting license every year and folks bitch and moan about that.