mcb
Member
So I finally finished a new pistol upper for my AR pistol last week and tested it successfully this weekend. I am actually pretty happy with it given the silly parts I have used to build it. It will be pressed into armadillo thumping duty is short order.
The whole upper started around a 5-inch 1: 5 twist 300 BO barrel I got for a steal. The upper is just a blemish Bushmaster upper I grabbed and the handguard is a DPMS tubular handguard the previous owner cut shorter for some reason. The barrel was thread 9/16-24 (slightly odd for an 30 cal AR barrel) but I got lucky and got the last AAC 51T 9/16-24 threaded suppressor mount. I even got that on sale and just before Remington Outdoor Company went belly up. The BCG is pretty much nothing special.
When I first put it to ether I had a SeeAll sight on it I got from a fellow THR member in trade. It work OK but I wanted a bit more. I picked up a Vortex Sparc AR recently and paired that with a Micro3X magnifier that moves between this and my other AR with a Sparc AR.
The big slow down on this build was the gas port was a place holder hole and was never correctly sized. The gas port hole was only .059 diameter and when I first put it together it would not eject, it rarely got the bolt back far enough to even get the end of the empty case out of the chamber and into barrel extension. It was a single shot automatic. So I needed to drill the gas port out. The barrel has been FNC'ed and my normal drill bits would not break through that very hard finish. I had to order some carbide drills. After a bit of research I settled on starting at #46 (.081) drill and I could step up to a #44 (.086) or #42 (.0935) if needed. At this point I had as much money in carbide drills as I did the barrel, but I got lucky and the .081 drill did the trick.
It now cycles with both of my subsonic loads with and without the suppressor mounted. And let me tell you the subsonic are still painfully loud from a 5-inch barrel without the suppressor. Should have worn my ears for those shots.
None the less the whole point of this thread is the short gas tube. None of the standard tubes pistol, carbine, mid, rifle length, would work with a barrel this short. I had to order a custom tube from White Oak Armament. For reference a standard pistol length gas tube is ~6.69 inches long. The tube I ordered for this build was only 4.775 inches long. White Oak kindly bent it for me but they put the bends too far apart and due to my barrel nut I had to ended up straightening and re-bending it myself.
So anyone with a shorter gas tube on a build?
-ramblin'
The whole upper started around a 5-inch 1: 5 twist 300 BO barrel I got for a steal. The upper is just a blemish Bushmaster upper I grabbed and the handguard is a DPMS tubular handguard the previous owner cut shorter for some reason. The barrel was thread 9/16-24 (slightly odd for an 30 cal AR barrel) but I got lucky and got the last AAC 51T 9/16-24 threaded suppressor mount. I even got that on sale and just before Remington Outdoor Company went belly up. The BCG is pretty much nothing special.
When I first put it to ether I had a SeeAll sight on it I got from a fellow THR member in trade. It work OK but I wanted a bit more. I picked up a Vortex Sparc AR recently and paired that with a Micro3X magnifier that moves between this and my other AR with a Sparc AR.
The big slow down on this build was the gas port was a place holder hole and was never correctly sized. The gas port hole was only .059 diameter and when I first put it together it would not eject, it rarely got the bolt back far enough to even get the end of the empty case out of the chamber and into barrel extension. It was a single shot automatic. So I needed to drill the gas port out. The barrel has been FNC'ed and my normal drill bits would not break through that very hard finish. I had to order some carbide drills. After a bit of research I settled on starting at #46 (.081) drill and I could step up to a #44 (.086) or #42 (.0935) if needed. At this point I had as much money in carbide drills as I did the barrel, but I got lucky and the .081 drill did the trick.
It now cycles with both of my subsonic loads with and without the suppressor mounted. And let me tell you the subsonic are still painfully loud from a 5-inch barrel without the suppressor. Should have worn my ears for those shots.
None the less the whole point of this thread is the short gas tube. None of the standard tubes pistol, carbine, mid, rifle length, would work with a barrel this short. I had to order a custom tube from White Oak Armament. For reference a standard pistol length gas tube is ~6.69 inches long. The tube I ordered for this build was only 4.775 inches long. White Oak kindly bent it for me but they put the bends too far apart and due to my barrel nut I had to ended up straightening and re-bending it myself.
So anyone with a shorter gas tube on a build?
-ramblin'
