You should look into the NRR of different muffs. I have both the MSA Sordin supreme Pro X and Peltor ComTac (MSA's are better IMHO). For indoor carbine shooting or sitting within a few feet of a bunch of muzzle breaks on comp guns I prefer to use cheap 3m foamies that have a NRR of 32db (orange ones in bulk from Home Depot) and my MSA's over top. The Surefire Ep3's are too tall for the MSA's and they hook and pull against the ear cup fabric, so they no longer see any use. If going with either Peltor or MSA buy the Gel Cup ear pieces, very comfortable and promote a better seal around your ear. The plus of electronics over foamies is you can dial the electronics to the max so you can at least hear something, i.e. corrections from your spotter or RSO commands. Trust me when I say, over the ear muffs may SEEM like they are enough, but for long periods of exposure they are not.