Went all thru the USMC, as well as prior to that went hunting ducks, partridge, rabbits, pheasant, quail, and deer, engaged in different shooting sports, and never even heard of shooting causing a hearing defect, that is until I went on the police department back in early 70's had to wear earing protection when on the range. Well in the late 70's,, was involved in an ambush, and my partner shot right close to my left ear in fact it was so close it left powder burns on ear lobe. I had ringing in my ear for at least two weeks afterward, anyway I could feel my hearing fading a little each year, to where I couldn't even decipher normal talk. Ended up wearing a hearing aid in each ear about 10-15 years later.
I've got a good buddy that has done more than his share of shooting and is in his early 80's and has never lost any hearing, so go figure, I to this day wish I could hear half as well as he does, maybe if it wasn't for that close encounter, way back when, oh well.
Now every time I go out shooting I have those type of hearing aids that knock out the sounds that are a certain amount over the decibels that are acceptable. Even so I still wear hearing muffs even though they feel somewhat uncomfortable, but I have to be able to hear my granddaughters when they talk to me.