AR Sponsor
Posted: 6/9/2006 4:19:39 PM EDT
My buddy is thinking about having a 20 inch cut down & threaded just past the front sight post. Will this work, or is there a certain barrel length required forward of the Gas/Front sight post? Here's an example pic of what I'm talking about: Thanks. |
|
Not going to work. You need at least a couple inches of barrel past the gas port. The absolute shortest barrel that will function with a rifle length gas system is about 15.8". I had a barrel brought to me for troubleshooting that was 15.65" and it could not be made to run with the gas port at 0.130" Keep in mind that the gas tube is only 0.125" inside so any larger than that will not gain you anything. For best reliability, I don't recommend going any shorter than 16.5" 17"is even better. This is not to say that an upper like that is impossible to make run. Just plan on a hidden gas system under the handguards. The front sight base would not have a gas port under it anymore. More info on gas systems here: www.ar15barrels.com/prod/gas-systems.shtml You should also read my post on how the AR gas operation works. How it works |
It's funny that you responded to this thread. I was just telling him that you could probably turn down his Bushmaster Dissy. Since you are local to us, he could drop it off with you. He basically wants to run a 16 inch barrel with full length handguard for the longer sight radius. Not to mention, that he has the older full length surefire handguard attached light he doesn't want to part with. He's been trying to decide the cheapest route (turndown or new LW barrel). |
$120 to turn down the barrel and add a mid-length gas port to the barrel while shortening, threading the muzzle and re-parkerizing the barrel. This requires that the barrel is large enough to accept a gas block back under the handguards. Then you will need a low profile gas block and mid-length gas tube. This will allow him to keep the rifle length surefire system and have a lightweight barrel with a mid-length gas system that is a little smoother running than a carbine gas system. We could also cut the barrel all the way back to the front sight base and permanent attach the flash hider to it. |
AR Sponsor