What should the bore diameter be on a 5.56 hider/brake?

[pneumagger]

So I'm finally getting around to installing one of my new Brakeout2 mounts on a 10.5" AR of mine. For a minute I thought I had grabbed the wrong mount because the hole looked HUGE for a 5.56mm - so I grabbed one of my 762 Brakeout2 mounts to compare. I'm pretty sure the bore is identical on them. Now, it's tough to get a caliper into them to measure the actual bore opening but a 30cal bullet easily passes through both with similar clearance. In fact, both will easily accept a loaded .308 cartridge all the way up to the cartridge shoulder... so the bore opening on this "5.56mm" brakeout has to be at least about .345"

I'm pretty sure AAC does not list a .30cal 1/2-28 Brakeout2 for sale... so I'm a bit confused.
Does a hole that large (.345"+) sound normal for 5.56mm hider/brake/comp to you guys?

The only thing I can figure is that the bore is universal for 6.5/6.8/300blk cartridges with a 1/2-28 barrel.

[T-Rex]

From looking at their website, it seems the only design change was the threads.

5.56mm=1/2x28
7.62=5/8x24

Same design, different thread pitch.

rsilvers should know the answer to this one

[pneumagger]

I was just surprised. Seems like max effectiveness for any 223/556 brake or comp would be something much smaller, but I've never owned a 5.56 brake until now so I just don't know.
I do have a 5.56 Blackout hider, and even it's bore is much smaller than the brakeout.

[Emilio]

I pulled out a old early production .556 brakeout (new in package old stock) and the back of a 1/4" drill bit fits almost snug but a 17/64 won't . My 308 FH's are bigger bore.

Hope this helps.