Quote Originally Posted by Ironman8 View Post
I know this is a necropost, but I didn't want to make a new thread and I think this discussion could add to the sticky.

Basically I was wondering if someone can tell me exactly what length each gas system is? I've gotten multiple different answers to this question through my research, so I thought I would ask here. I'm really only inerested in carbine and midlength port locations, but for the sake of information, if you know them all, then list em
There are multiple answers to this question based on what your refernce points are. From a simple perspective, carbine length handguards are 7", mid-length are 9". Gas port position would be slightly beyond the end of the HG.

From Armalite's data, the length of their gas tubes for carbine and mid-lengths are 9 3/4" and 11 3/4" respectively. Note that the gas tubes extend rearward of the barrel extensions a bit, so from a HG perspective we're measuring from the delta ring forward, and from a gas tube perspective, we're measuring the length of the tube.

Finally, not sure if Armalite is consistent with the rest of the industry , and for that matter, while I'm under the impression that the industry has standardized port locations on carbine-length gas systems, I'm not sure if there's industry agreement on mid-length systems. I would need to hear from an industry SME regarding the latter.