I prefer the Peltor Tactical 6 Ear Muffs. They are electronic so you can hear normal range commands but shut down at the specific decibel level. And they also and have contoured Side Designed Ear Muffs for rifle shooting. I have two pairs and have used them for years on rifles including M-14, M-16, AR-15, bolt guns and all. You might want to take a look at them.
Another issue is that people think ear protection that goes in your ears are totally safe when they are not. The Bones on your head around your ears pick up vibration and sound just the same. The reason I can prove that is when on SWAT 16+ years we used bone mikes that were in contact with the bone on your head in front of your ears. We could actually whisper to each other and could hear through the bone just as well as through the ear canal. Just some insight when selecting protection.
Also in the hot weather when we sweat the seals on the muffs and our head also have a tendency to break seal more easily at this time of year. You can also always double up with a set of plugs and muffs which I do at the academy since the overhead and walls are concrete and block!