Considered the SLR but prefer the simplicity of the Govnah.
No, it's unverified. Have seen a lot of people claim this, though, for the Colt 694x 10.3" barrels.
Contrast this to people who claim to have spoken to sources at Colt who state their MK18 barrels use a .068" gas port. Which would make sense, since .mil uses 5.56 and nonmil and LE often uses .223 instead.
True, but the majority of what I use is .223, so I want to err on the side of the port being a little bit bigger. Amphibian of MicroMOA sizes the holes in his regulator plates .003" larger than what he recommends for 5.56 if one is using .223, so that is where I came up with how much larger I would want to go than the MK18 spec.
Another piece of the puzzle, it is widely reported that the newer DD Mk18 barrels use a .078" port, and they are still overgassed for .223, so I don't want to go quite that large of a port.
As you are probably aware, in WA, individuals can no longer do their own F1 SBR builds at this time due to how BATF is interpreting I594.
So, until that changes (if ever), individuals to instead go through a manufacturer to make the SBR, do a F2 (or vice-versa), then transfer it back to the individual on a F4.
You supply RA with the gun and/or parts, they do the mods, and they submit the F2 and F4 to BATFE.
Gunz,
I want it to work with .223 ammo (though not the lower powered of the .223 loads), since I do not typically use 5.56 NATO ammo any more.
My understanding is that it would be beneficial to open the gas port slightly more than the Crane spec of .070, for unsuppressed use.
Is that not the case?
FYI, this particular barrel was from a special run that Stag did, has a 5.56 NATO chamber (though I haven't checked it with a 5.56 chamber reamer) and the rifling is 1/7, so hoping it will stabilize bullets when cut to 10.3, and not have any problems with extraction due to the chamber being tight. I have shot it with M855 and M193 and not had any problems with popped primers.
Clint at BRT says the same thing, that .003" is about the port size eqivient to the difference between .223 and 556 chamber pressures for the overall pressure curve in maintaining an appropriate margin of reliability in function. Which is why for mixed use 223/556 unsupressed he recommends a .073" gas block insert when using 10.5" barrels over the crane spec which accounts for exclusively using 556 Nato pressure ammo.