After an afternoon with the .357 sig, I started thinking about my hearing protection-alot. Here is my question. I took apart my Bilsom compacts and looked inside. there was the plastic shell of the muff itself, the seal-which fits around the ear, the dampening material- which was the concerning part. This inner material was only about 1/2" in thickness of pulled cotton batting and a super thin 1/8" piece of sparse foam. Now I think these things actually had a good NRR. It could be improved upon. So, how do you think that spray foam filler from home depot would work for sound dampening? Or, could you think of anything better? I also pondered stuffing that acoustical foam inside were the old batting is. Also, which is the best muff? Thanks for your indulgence.