I’ve heard the Surefire MB556AR muzzle brake increases decibel levels at the shooter’s ear more than most average brakes. My question is, has anyone tested it, and if so, exactly how much louder is it?
Also, does anyone know the internal diameter of MI’s free floating rails? They feel pretty wide on the outside, but I never bothered to pay attention to the internal clearances.
What length barrel are you talking about?
A 14.5". Any barrel length will work as a general example though.
I’m not an engineer. But I’m going to wager that on different barrel lengths the Muzzle break is louder than it would be on others. I would also guess that as we go with a shorter barrel the muzzle break makes it worse for the shooter than if no muzzle break was present.
I will tell you from personal experience the Surefire mb556k on a 10.5 inch LMT takes an other wise controllable shorty and makes it damn near unmanageable. The sound isn’t as much of an issue as the concussive blast and fireball.
http://www.vimeo.com/1522585?pg=transcoded_embed&sec=1522585
Excuse my laughing.
I would go with the other adapter, the flash hider one if you can get away with it.
Yeah, I’d expect it to be “louder” on a 10.5" than say a 20". That muzzle blast does seem a little excessive, so maybe I will look for another route.
Make sure you carry a fire extinguisher with you when you go shooting in the woods with that thing. 
They are pretty loud and to be honest, if you are NOT using the SF can, I see no use for running the SF MB (or any MB for that matter).
C4
I fixed it for you. There are a little more than 74 million Americans residing in states that prohibit flash hiders. People who don’t reside in AWB states tend to forget that nearly a quarter of us do and have to make our gun choices accordingly.
There are better MB choices out there than the SF that is not so obnoxious and has a lower flash signature. 
C4
I’ve never been able to get an answer to this, or height/width, out of MI via email (or Troy ow SWS either for that matter).
That’s a cool video. I wish there were more rounds fired though.
Recommendations?
Not Grant, but the the PWS flash suppressing comp and the EGW Gen II comp are two that are quieter and create less flash than the surefire. The surefire is more effective, but then again it is only a 5.56 and recoil isn’t that much of an issue to being with.
VLTOR and PWS.
C4
The plan would be to buy the muzzle brake first and have it perm’d to the 14.5" barrel so it can be shot while waiting for the suppressor to go through.
I’ve never been able to get an answer to this, or height/width, out of MI via email (or Troy ow SWS either for that matter).
That sucks. I want a two piece rail with hefty enough internal clearances to fit a suppressor. Of those I’ve scoped out, MI is the lightest. I’m pretty sure I’ve seen MI’s ran in tandem with a suppressor, but I’m not willing to bet the cost of a rail on it. 
I highly doubt it would fit a 5.56 can
FF Rail Chart
5.56 Suppressor Chart
I thought Surefire advertised the MB556AR as the diffusion muzzle brake that reduced side blast and concussion. All muzzle brakes will increase noise dB levels to some extent versus no muzzle devise at all. How do the OPS comps measure up?
The only measurement I’ve found is for the non FF MI’s and the internal diameter is 1.79", but of course it’s narrower at the end cap. Add in that the FF’s likely have extra meat up front to accommodate the fastening hardware, but I can hope.
If the DD M4 is 1.45, I’m still thinking (hoping) the MI could have more clearance.
Great charts by the way. 
Looks like you may be in luck!
(I think he means 2.4", BTW, there’s no way they are 1.43" OD and 1.75" ID)
Got a reply from MI. I’d still find a way to double check fit before spending lots of money, but
Outside is 1.430 square
Inside is 1.750q
Awesome. I’d assume he does mean 2.4" as that’s what the non FF rail is rated at OD.