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Hey all, I have a 300 AAC Blackout AR pistol I built a few months ago:
http://www.xdtalk.com/forums/ar-talk/254438-build-number-2-300-aac-blackout-8-pistol.html
Anyways, it has been giving me nothing but grief. I tried 2 different bullets each with 2 different powders, as well as some remanufactured ammo from a place 20 minutes from me. I got one set of my reloads, as well as the remanufactured ammo working from a benchrest.
However, when I progressed from benchrest to firing upright, it quit working again, at least sort of. Everytime I fired it like a pistol (aka no support other than two hands on it, it would eject the spent case, but not chamber a new round. I individually tested each of the few mags I use with this gun by single firing a round in the mag, and the mag locked back each time, so the mags should be good. I also inspected the chamber for any irregularities and didn't find or feel any.
I figured out that if I fired it with it shouldered (which doesn't feel to good since it jams the tube into my AC joint), it cycles sometimes.
I guessed that it was overgassed so I bought an H2 buffer knowing I could make an H buffer out of that and my carbine buffer. I took it out two weeks ago with the homemade H buffer. Also put extra oil on the BCG, since I know that can be a problem for some ARs. Suddenly the same exact handload that would not cycle with a carbine buffer would cycle every time, but not lock back on empty (with the same mags that I individually tested). However, when I shot some more of the remanufactured ammo, it would no longer cycle.
Confused as could be, I went and bought some 125 gr OTM Remington Premier Match ammo, I took apart and reassembled the gas block and gas tube, and went out today with the H2 reassembled and the carbine buffer. With the H2 buffer in it, I fired 5 rounds with it shouldered. It cycled twice, I had to charge it twice because it ejected but didn't strip the next round, and it didn't lock back on empty (same mags that were test and worked, then stopped working when I added oil). I fired it like a pistol 3 times, and it only ejected the spent case, but didn't strip the next round (didn't reach the bottom of the 5 rounds loaded cause I got frustrated. I switched to the carbine again, and fired 5 rounds from my shoulder. 3 ejected and didn't strip the next round, and 1 started to, but didn't finish. It also didn't lock back on empty.
So now I am lost. I am assuming my BCG is sensitive to too much oil, as it stopped locking back, so next time I won't oil it as much. I will try the H1 buffer with the match ammo shouldered.
Any other ideas? Why won't it work like a pistol? I want to buy a Sig brace since it seems to work better supported, but I feel as if I might as well set up a trust and SBR it if I am going to do that, and I don't want to waste money on an SBR that won't shoot.
I am open to any and all suggestions, as I am at my wits end on this.
http://www.xdtalk.com/forums/ar-talk/254438-build-number-2-300-aac-blackout-8-pistol.html
Anyways, it has been giving me nothing but grief. I tried 2 different bullets each with 2 different powders, as well as some remanufactured ammo from a place 20 minutes from me. I got one set of my reloads, as well as the remanufactured ammo working from a benchrest.
However, when I progressed from benchrest to firing upright, it quit working again, at least sort of. Everytime I fired it like a pistol (aka no support other than two hands on it, it would eject the spent case, but not chamber a new round. I individually tested each of the few mags I use with this gun by single firing a round in the mag, and the mag locked back each time, so the mags should be good. I also inspected the chamber for any irregularities and didn't find or feel any.
I figured out that if I fired it with it shouldered (which doesn't feel to good since it jams the tube into my AC joint), it cycles sometimes.
I guessed that it was overgassed so I bought an H2 buffer knowing I could make an H buffer out of that and my carbine buffer. I took it out two weeks ago with the homemade H buffer. Also put extra oil on the BCG, since I know that can be a problem for some ARs. Suddenly the same exact handload that would not cycle with a carbine buffer would cycle every time, but not lock back on empty (with the same mags that I individually tested). However, when I shot some more of the remanufactured ammo, it would no longer cycle.
Confused as could be, I went and bought some 125 gr OTM Remington Premier Match ammo, I took apart and reassembled the gas block and gas tube, and went out today with the H2 reassembled and the carbine buffer. With the H2 buffer in it, I fired 5 rounds with it shouldered. It cycled twice, I had to charge it twice because it ejected but didn't strip the next round, and it didn't lock back on empty (same mags that were test and worked, then stopped working when I added oil). I fired it like a pistol 3 times, and it only ejected the spent case, but didn't strip the next round (didn't reach the bottom of the 5 rounds loaded cause I got frustrated. I switched to the carbine again, and fired 5 rounds from my shoulder. 3 ejected and didn't strip the next round, and 1 started to, but didn't finish. It also didn't lock back on empty.
So now I am lost. I am assuming my BCG is sensitive to too much oil, as it stopped locking back, so next time I won't oil it as much. I will try the H1 buffer with the match ammo shouldered.
Any other ideas? Why won't it work like a pistol? I want to buy a Sig brace since it seems to work better supported, but I feel as if I might as well set up a trust and SBR it if I am going to do that, and I don't want to waste money on an SBR that won't shoot.
I am open to any and all suggestions, as I am at my wits end on this.
