Quoted:
I woudn't doubt if every branch of service uses a different mount, or a few differnent mounts on different models. If they are buying a rifle scope combo from Barrett, then maybe Tony would know what they put on them. Sometimes it may be someone sitting behind a desk that chooses what brand or make of product that is chosen using a set of  standards and price range.
Night Force, Badger and most heavy duty rings with at least 4 screws on the top mounts will work. There are some nice alluminum ones out that work well.
I prefer the Night Force myself, they have never failed me for 13 years on 6 rifles. I have had a couple different inexspensive brands slip from recoil but never had that happen with a good set of lapped Night Force rings. A bit pricey but worth every penny just like their scopes.
I have put them through torture tests before like 4 straight days of sunup to night firing with over 1800 rounds of ammo in hot sun, wind, dust, humidity, and rain with no failure. Just follow the supplied mounting and torqing instructions when mounting and lap.

Ed

Quoted:
Contact Ed @ versa pod he is the military sales consultant. I have a set of their rings and they are by far the best rings you can have on the fifties. they are solid one peice machined steel and will never break. they carry a lifetime warrenty. Tell him Tim Bowen told ya about them and he will cut you a better deal.