16"er's are pretty standard throughout the industry. But they're not exactly "short".
Short =
Armalite AR10 w/12.5" Noveske barrel.
POF P308 w/12" barrel. Piston driven.
DSA OSW w/11.5" barrel. Not an AR, it's a FAL, but still a SBR 308.
The POF and the DSA have adjustable gas systems. Whereas the Armalite does not. But they all run without any issues. At least.....so far.