Double plug. Put ear plugs in and then the muffs on over the ears. For recoil increase the weight. On my AR I have the A2 stock with a 4 lb. lead weight in it. Between that and the stainless steel barrel it weighs in close to 14lbs. I use it for target shooting, prone and bench, so this set up would not be fun to hump through the woods or shoot standing. But double plugging will help with the noise if it bothers her.
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