Proper use of what kind of hearing protection? You need to make sure you have good ear plugs that are form fitted to your ears, not those useless foam things or off the shelf cheap ones. If you are really concerned use the form fitted ear plugs and wear the ear muff versions in addition.
Wear the ones with speakers and blast Led Zeplin,that shout help cancel out the gun noise
Both earplugs plus earmuffs should work a bit better. I wonder whether the NRA would have some answers.
I also know that there are earmuffs which are good out to 99 db. They are expensive but in your case probably worth it. The local indoor range uses them. No idea who makes them.
I would stay out of indoor ranges too. And if you can avoid a range or lanes which have roofs it would probably help.
bump