Gas port Sizes

[jmart]

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.

[Ironman8]

Well I don't know how port LOCATION (not size) is measured, but I would logically think that the location would be measured from bolt face. I didn't include that in my first post, because I didn't know how they were measured (length-wise) and if there was even a standardization among the industry.

If they do measure from bolt face, then what I am looking for is:
The carbine gas port is 7.x" from bolt face
The midlength gas port is 9.x" from bolt face
....ect

I have seen lengths posted for the carbine gas system anywhere from 6" (which I know isn't right) to 7.8". This lead me to my question. Is there not a standardization?

[AR15barrels]

There is standardization on the distance from the bolt face to the barrel extension's front face.
There is standardization of the distance from the barrel extension front face to the rear of the gas block seat.
There is standardization of the distance from the rear of the gas block seat to the center of the gas port.
Not all companies follow the standards.

If you added these figures up, you would end up with the following figures:
Carbine is 7.795" from boltface.
Mid-Length is 9.795" from boltface.
Rifle is 13.170" from bolface.

[Ironman8]

There is standardization on the distance from the bolt face to the barrel extension's front face.
There is standardization of the distance from the barrel extension front face to the rear of the gas block seat.
There is standardization of the distance from the rear of the gas block seat to the center of the gas port.
Not all companies follow the standards.

If you added these figures up, you would end up with the following figures:
Carbine is 7.795" from boltface.
Mid-Length is 9.795" from boltface.
Rifle is 13.170" from bolface.

Thanks! PM sent

[fixit69]

Well, necronecropost.

I saw this and I would like to touch on the GAS PORT sizes.

Not finding much, just general stuff. Here's what I'm thinking:

Cutting down a 14.5"DD (carbine?) to 11". So, I see what size. But it got me to thinking (dangerous). Is there a tried and true method for all barrels for porting? I am thinking there must be. I used the magic orange button, which usually answers all my questions, but I must be missing somthing. Not looking for the absolute, just a guide if i want to go shorter. Do it yourself sucks somtimes, as my funds are limited.

So in closing, HELP!

ETA: Suppresor added to the mix also. If my first question wasn't bad enough...