I really like the 7.62 MAMS, and IMO it is the best 7.62 brake out there. I've shot it quite a bit on my EMC, which I've also shot with the original M110 FH. Additionally, I've shot another ECC with a Surefire MB, plus I've stood next to guns being shot by somebody else.
My impressions:
The MAMS obviously reduces the felt recoil and muzzle rise compared to the FH quite significantly. Conversly, the FH also is more effective at reducing muzzle flash as compared to the MAMS.
That being said, whats most important is the comparison with the Surefire MB. Between those two, I would say felt recoil is identical. As far as muzzle rise, the Surefire does a great job as long as the rifle is held and fired level. Should you tilt the rifle - i.e. to fire with an offset site, around a barricade, etc. then it will "push" off square to the rifle - which depending on your position may pose a problem. A great example of this happened during a LAV battle rifle class; one of the students had a 7.62 AR with a Surefire MB on it and they had a 45 offset red-dot. When he tried to shoot quick drills up close with the offset redot, the surefire kept pushing the off slightly - slowing him down. While he was running the drill, we could all see what was going on - it was that perceivable. The MAMS doesn't really have this problem - hence why it is called the MAMS (Multiple Axis Muzzle Stability).
As far as flash suppression, I definitely feel that the MAMS is more effective than the Surefire MB. Now, where the MAMS really shines is the concussion. To the shooter, the MAMS is by far more pleasant to shoot. It doesn't beat the shit out of you, like shooting the Surefire MB on a 7.62 gun for an entire day. To a bystander, the MAMS is still much better than the Surefire. While the MAMS has more blast than compared to the FH, it has much less than the Surefire MB. Now, standing next to a MAMS being shot on a 7.62, still has decent concussive blast - but it is significantly better than the Surefire MB.
