No, not all that criminally.
About 40% from family and friends. This ugly statistic fuels the argument for a NICS check every time. But, like was said, being a BG doesn't mean prohibited.
About 15% just buy them normally with a NICS check anyway. And if you look back at all the "mass" shooters, most did, and used legal weapons. NICS isn't really that big a deterrent if you can pass it and still get a gun. We will NEVER be able to predict which buyer will go rogue and start shooting up the neighborhood.
The other component is from "off the street." Another 40% - which comprised mostly stolen guns. Where did those come from? I'm going to suggest that many didn't get taken out of a locked gun safe in the back closet bedroom of suburbia, UNLESS you were showing it off in the last six weeks and that friend of your buddies came back. After all, you pretty much showed him were it was and how easy to get in, which is statistically quite high in home burglaries.
Guns from cars? Yes. Guns from stores, pawnshops, etc.? Sure. I was working Montgomery Wards in the '80s, a guy came into the store late before closing, lifted the glass off the display case and left with a new stainless Smith 6" .357 and a .38 snub. It's not real hard when dealers leave guns in retail display cases. The glass was intact and unbroken.
All you have to do is be bold - and the citizen in Wichita? "Heroics" describes it best. He was lucky, the last guy I heard of was gunned down from behind in a Walmart.
Permit or not, protecting someone else's property isn't your mission in life - you very well may be deprived of it, and for what? Before we anoint this particular good guy let's ask the other guys wife and family what they think about their dead husband and his heroism. I will, in fact, ask you to tell your spouse and family about it, so they will at least know beforehand. And be prepared for some resistance accepting the idea.
Let's not forget dead heroes don't pay the bills and our family has to move on. Are you fully prepared to die for a few cheap rifles from a sporting goods store if the perp has a backup and both draw down on you? You might be giving them street cred in the gang they want to join, the guns were just icing on the cake.
You cannot possibly know or have all the facts in hand, and you won't have a bird's eye view. You only get about half of the information you'd like to have and it's a game of chance.