I didn’t know this, did you? From another forum.
Picking a QUALITY barrel is much more important.
That is straight up common sense. A crap barrel is a crap barrel, gas system be damned.
That is interesting that it was designed for the 10". I thought I’d read that the dwell time is very similar between the 20" rifle and the 14.5" carbine, so I assumed that was by design.
IIRC I think I read somewhere that it was originally used with the 10 or 10.5" barrels but after some research it was found that 14.5" was more reliable with the carbine gas system length.
14.5 was so they could mount a Bayonet.
The original 10’s used a moderator or ‘booster’ to give back-pressure. They were increased to 11.5 to enhance reliability.