View Full Version : AR carbine with rifle-length gas system?

gun toting monkeyboy
09-07-2010, 4:52 PM
Ok, I was cruising Midway with thoughts of abusing my wallet when I came across a DPMS 16" barrel with a rifle length gas system. I was under the impression that a set up like that didn't work well because there was not enough gas pressure with the gas port located so close to the muzzle. But none of the reviews mention any problems like that. Randal (AR15barrels) had an article on it a while back explaining the hows and whys of it all. Is this just a gimmick barrel by DPMS? Or did they somehow manage to get around the problem? I would love to try it out, but I can't see spending money on something that I was told wouldn't work. Does anybody have any input on this barrel?


09-07-2010, 5:06 PM
They open the gas port up HUGE on those barrels to get them to function.
It will work with good ammo, but don't be suprised if it won't run weak ammo.
Also, don't expect it to work well on cold days when pressure is lower.

gun toting monkeyboy
09-07-2010, 5:21 PM
That's about what I figured. :( Thanks for the quick response.

09-07-2010, 9:32 PM
You could probably also put something like a KX3 or a Levang to give it a little more back pressure to help it cycle. Nothing with open ports, but with large expansion chambers. Same concept as the various Krinkov brakes and the 3.5" and 4.5" moderators for the XM177 and 607 guns.

09-07-2010, 9:59 PM
I didn't read rifle length gas anywhere in the description. Is that a true rifle length gas system or is it just a dissipator barrel?

09-07-2010, 10:03 PM
i thought that's what a dissipator was... (rifle length gas system on a carbine length barrel)
am i mistaken about that?

09-07-2010, 10:17 PM
I didn't read rifle length gas anywhere in the description. Is that a true rifle length gas system or is it just a dissipator barrel?

DPMS is the only company that I know of that produces a 16" barrel with a rifle gas system.
Most anyone else would not go shorter than 18" on the rifle gas system.
I don't recommend going below 17" and even those can get picky as to how wide a RANGE of pressures they will work with.

You can tune any barrel to run with any ammo, but the gas port diameter will not be the same for all different types of ammo.
As there gets to be less and less barrel past the gas port and the gas port gets larger and larger, the tuning bandwidth of what ammo will work gets narrower and narrower.

09-07-2010, 10:18 PM
i thought that's what a dissipator was...


A dissipator is Bushmaster's name for their 16" carbine gas system barrel with a cut down gas block and then a regular front sight base located at the rifle position.


09-07-2010, 10:25 PM
the bushmaster dissipator upper has the front sight as a dummy just for mounting the handguards and the real gas block is under the handguard. It uses the car gas system so it is reliable enough. ive fired about 1000 rounds of wolf through mine in winter and summer temps and havent had any problems.

09-07-2010, 10:33 PM
Why would DPMS build such an odd barrel?

09-07-2010, 10:36 PM
my guess would be to reduce cost of production. cutting corners usually gets you an inferior product as we all know.