As soon as I hear, "I used to be.....", I immediately ask "Why do you need to appeal to authority?".
I was once in Cabela's and overheard an "expert" employee explain to an inexperienced new buyer looking for a home defense gun "Check out this pistol grip shotgun. You don't even have to aim. Just point it in the general direction, and you'll hit 'em."
When I asked him if there was something special about that particular shotgun that caused the pattern to open up in only a few feet, because the biggest room in my house is a fairly large 18 feet and I doubt either me or a burglar are going to kindly back away from each other until both our backs are against the wall. Add in 2 feet for the length of the shotgun, and that wad will have to violently explode an inch from the muzzle to open up far enough to "hit 'em without aiming".
The clerk just looked at me and said, "I've been working here for 15 years. I'd say I'd know a bit more about firearms than you."
I just turned to the potential buyer and said, "He's willing to bet blind without any clue about my credentials that he knows more about home defense, and he's using your safety for currency. He sounds more like a gambling salesman than an expert. Seek professional advice for your first gun purchase."
I then walked away.
Some folks are so enamored of their own knowledge, they don't need to compare it to anyone else's to see if there's more to learn.