NRR is everything
I personally don't like muffs as I find them uncomfortable for extended shooting sessions. The cheap disposable twist-squish-insert foamies work well but I use custom molded ear protection as I can remove them and re-insert them easier (with one hand) when I go into the shop, etc. That's what works for me, but all that really matters is the NRR. You should get something as close to 30 as possible. We are dealing with firearms here and even magnum loads in your case. The impulse noise/shockwave/percussion has much more potential to cause damage that power tools, machines, loud music, etc. For the ultimate protection, use foamies with a good NRR, along with muffs with a good NRR. Remember, NRR of 30!!!