Surefire Legacy break mounting question

[Desert Rat]

First off excuse the ignorance on this question I am in no way a gunsmith. I’m doing an AR10 build And would like to throw my surefire legacy break and can on the gun. The surefire break threads on the barrel fine and feels solid yet it has that iconic shroud (see pics) Im curious whether I can just thread the brake on and be done with it or whether it was originally designed to shoulder against the barrel itself. In other words I would have to have the barrel contoured specifically. Thanks everyone in advance.

 

[longshot2000]

What you have is the break made for the M40A5 and A6, and I suppose you have the legacy can (before SOCOM). The break is designed to go over the barrel, and the end of the brake is where the suppressor connects and forms a seal, and then you turn the ratchet device on the suppressor. So, I think you are fine, if the threads are tight. Aesthetically, there is just something wrong about having a fluted barrel with that brake, but it will work.

 

[Desert Rat]

What you have is the break made for the M40A5 and A6, and I suppose you have the legacy can (before SOCOM). The break is designed to go over the barrel, and the end of the brake is where the suppressor connects and forms a seal, and then you turn the ratchet device on the suppressor. So, I think you are fine, if the threads are tight. Aesthetically, there is just something wrong about having a fluted barrel with that brake, but it will work.

I’m actually going to be putting it on a proof research barrel that was just an example barrel. So hopefully it will look a little better

 

[nn8734]

That brake and other OTB mounts like it must have .250” or so between the rear end of the brake and the step back where the non-contoured portion of the barrel meets the contoured section so the suppressor’s mounting collar can fit onto it and lock up without interference. This applies if the muzzle end of the barrel has a diameter greater than the brake’s inner diameter.

Special contouring usually isn’t necessary when these are used on semi auto barrels but almost always required on bolt gun barrels.

The M40A5s and A6s all have this clearance included in the overall length of the barrel contour.

 

[Mendy300wm]

What’s the OD of that proof research barrel at the end?

 

[Desert Rat]

What’s the OD of that proof research barrel at the end?

 

[Mendy300wm]

Good to go. ID of those breaks is .775