Search for hunting hearing protection on the web. I've got some from Walker's and while they're not quite like your natural hearing- they're not bad at all. It made me focus more on observation than having to only rely on hearing that was damaged from artillery and grenade bursts!
The tape idea or the hose clamp ideas... ummmm nope- not for me anyways!
An AR platform rifle's muzzle brake can be removed with not much difficulty and replaced after the hunt (not sure about a bolt action though) and that would certainly reduce the amount of sound coming back at you (hearing protectors would be better- IMHO).
I'd suggest some kind on thread protector- electrical tape would well for that and wouldn't be blown off with the shot- but you'd want to ensure the threads weren't damaged... Just a thought.