Something I’ve found out after almost a year on the other side of the gun counter: If you want to work in the industry, having some knowledge about a bunch of firearms related things trumps knowing every little thing there is to know about, say, the AR-15. You never know who is going to walk in the door / send you an email / call on the phone, so being able to talk intelligently about sporting clays with one guy and then switch over and chat about concealed carry for women five minutes later is a very, very useful skill.
And not just “Yeah, my Dad had a gun like that, but I never shot it” type conversations, either. If I have one piece of advice for anyone who wants to get into the industry, it’s shoot a bunch of guns in a bunch of different settings. Don’t just go to one range and do one type of shooting all the time: If you plink, try shooting clays. If you shoot scatter guns, try precision rifle. Take a good pistol course. Shoot 3 gun, bullseye and go hunting. Learn a little bit about a bunch of things, because that helps you understand HOW your customers use their guns, and that helps you sell them the guns they want and or/need to enjoy those activities a little bit more.