A2 bird cage question

[WHSmithIV]

Anybody happen to know if a .223 A2 bird cage flash hider and a .308 bird cage flash hider have the same external circumference? I'm thinking that since the barrels for .308 and .223 can be had for .750 gas blocks for both that they might.

[DutyUse]

Not sure of the Outside measurements, but I can tell you that they will have different thread patterns. .223 being 1/2x28 while the .308 is usually 5/8x24.

[WHSmithIV]

I know the thread patterns are different. Just need to know if the outer dimensions are the same.

[UWone77]

There's no standard for 308 bird cages. Depends who's making it. In my experience they are larger. How much larger, I don't know.

[mustangfreek]

I have a standard 223 and 308 A2 sitting here if you want any numbers..

[WHSmithIV]

Thanks mustangfreak - could you just take a ruler and measure the diameter of the end of the two bird cages for me? What I'm trying to find out is if an M7 bayonet will slide over the .308 birdcage.

[GRIFFIN ARMAMENT]

The tolerance on the nato print is .860+.004-.000. The 5/8-24 30 cal version is not an a2 but rather something that looks like an a2. Ive seen examples that do fall inside the diameter tolerance but the grooves are much larger to accomodate the larger id thread.

Interesting point- they seem to suppress flash better in 308 than 556 because the 30 cal unit has the same .343" id hole with the larger 308 bullet. The 5.56 version uses that hole to accept the bfa spigot and probably loses a lot of efficiency for it.

A proper size id hole for 5.56 would be ~ .255" for the purpose of flash suppression.

[WHSmithIV]

Hmm... might be a good idea to make A2 flash hiders with the .255 id hole. Thanks for the info.