Hi there everyone,
Does anyone know the GP sizes of BCM midlength barrels? Not even their exact size, but if the 14.5" and 16" barrels are the same?
I’m looking to recreate a Noveske Afghan with a BCM SS410 barrel, but they only come in 16". I wasn’t sure if cutting it to 14.5" would undergas the gun or if, on the predication that the CL midlength barrels have the same gas port, it would still function so long as I avoided underpowered ammo.
Anyone know?
I know the 14.5" is .076, and I’m pretty sure the 16" .072.
Thank you! So cutting down a 16" to 14.5" would most likely undergas the gun. Dang.
That’s why they invented reamers
I think you’ll be fine.
Cutting the 16" down WILL decrease the gas drive, but Noveske usually runs their ports a little larger to cycle rifle/H2 buffers easily.
That should put the size right where you’d like for a 14.5"
Off the top of my head it is around .076 for both. You will be fine.
ETA: A midlength should be able to function with an H an even H2 if you are shooting MILSPEC ammo.
And you can swap to a lower weight buffer to tune things… I wouldn’t lose sleep over it.
Perfect. Thanks IG/everyone else. 
I’ll let you all know how it turns out. I’ve got a bunch of buffers ranging from carbine to H3, so I’ll be able to tune it pretty well, I think.