6mm ARC

[am4966]

That's cool but I'm still going to test and see if normal gas lengths will work. If I do get one it will be a 12 inch.

I believe it was Lantac who tested a 11.5” n 12” ARC barrels and they went with a carbine gas systems. Imo this tells me that short barrels don’t need the longer than normal gas lengths but with longer barrels the gas system needs to be bumped up one. 14.5” rifle and 18” rifle +1 and I thought with the 22”-24” they used a Rifle +2(not a 100% on that)

I’m wanting a 18” upper but a 12.5”-13.5” upper with my SBR’d lower would be sweet too!