I’m in the research phase of doing a 6.5CM AR build. I’ve read that with barrel lengths longer than 22”, a ‘rifle+2’ gas system is recommended due to the cartridge being higher pressure than .308. Is an extended gas system also recommended for 20” as well? Thanks.
No not necessary. On a side note, I have a 24" standard rifle gas that runs fine too, so it isn’t technically necessary even for the longer barrels, although it is probably more "optimized’ to run the rifle+ length.
I’m running Ballistics advantages 22" barre in 6.5 and have zero issues, I have about 2675 round through two barrels.
Another 22" BA barreled gun with no problems.