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Posted: 7/9/2016 3:15:15 PM EDT
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So, over the last year or so I have assembled a MaTen to the following specs:
Mega MaTen Upper and Lower Set Barrel: Rainier Arms Match .308 Barrel – 16” DPMS BCG: Rainier Arms Ultramatch .308 BCG Hand Guard SLR DPMS High/SR25 14" 308 SOLO SERIES HAND GUARD – MLOK Gas Tube: SLR BLACK NITRITE MID LENGTH GAS TUBE Gass Block: SENTRY 7 CLAMP ON PREMIUM ADJUSTABLE GAS BLOCK-MELONITE Trigger: Geissele SSA Stock: Magpul ACS-L Carbine Stock Buffer Tube: PWS Enhanced Buffer tubes DPMS .308 carbine buffer & .308 carbine spring Magazine: Magpul 10 round magazine. Ammo: Federal 7.62 x 51mm, 149-gr. FMJ bullets First trip to the range, it fired and ejected the casing, but would not load the second round. I forgot a wrench to adjust the gas block, so went home. Last week, went back to the range, same deal. Opened gas block all of the way. 1.Weapon fires first round, ejects first round, but will not load next round. 2.Loaded one round into magazine. Weapon fires first round, ejects first round, but will not lock open on empty magazine. Troubleshooting so far: 1.Insert empty magazine and manually cycle BCG. BCG will lock on empty magazine. 2.Inserted two dummy rounds into magazine. Manually cycling the BCG will load the first round, eject first round, load second round, eject second round and lock on the empty magazine. Each round ejects fully. I assume the gas block is not seated properly over the gas port. I intend to remove the rail and gas block to re-install the gas block. I will check the size of the barrel gas port and use the UNIQUETEK - AR-15 GAS BLOCK ALIGNER from Brownells (never used it before, but I want to ensure it is lined up). I also have some different 308 ammo to try, but the 7.62mm ammo should be cycling the BGC. Anything else I could / should check before or during this process? I really don’t want to take it apart 2-3 times to fix it. |
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For $9.00 bucks, this little do dad is hard to beat for aligning a gas block: http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/gas-system-tools/ar-15-gas-block-aligner-prod68371.aspx
I have installed many a gas block and have use all kinds of ways to align them...air compressor, measure and mark with a pencil, just eye balling it, etc. but I am. Ow spoiled by that alignment tool. I would also check your gas rings on the bolt. I recently put a small frame AR together using a JP upper and they use a one price gas ring now days. I was having the exact issues you are having. Turned out that one piece gas ring was to "loos". Put standard rings on the bolt, and no more short stroking. Also check to make sure the gas key is tight. Good luck |
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I had a similar issue with my second MA-TEN and I was able to swap working parts to see
I checked alignment with gas port (it was perfect) and then I was able to take my first BCG with me to the range and a second set of buffer/spring combo. the first thing I did at the range was swap BCG and it worked each time. I sent the original, new BCG back and got a replacement. was allowing to much gas to escape before unlocking. gas rings?? |
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What buffer and spring are you using?
Take a picture of the gas tube from the bottom of the upper receiver when it is separated. Your gas tube might be too short. There are several different "MLGS" AR10 gas tubes. If yours is short, it will produce the malfunction you are having. (I've been shooting and working on AR10s, SR25s, LR-308s for 13 years now, have owned and fixed many.) |
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Quoted:
For $9.00 bucks, this little do dad is hard to beat for aligning a gas block: http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/gas-system-tools/ar-15-gas-block-aligner-prod68371.aspx I have installed many a gas block and have use all kinds of ways to align them...air compressor, measure and mark with a pencil, just eye balling it, etc. but I am. Ow spoiled by that alignment tool. I would also check your gas rings on the bolt. I recently put a small frame AR together using a JP upper and they use a one price gas ring now days. I was having the exact issues you are having. Turned out that one piece gas ring was to "loos". Put standard rings on the bolt, and no more short stroking. Also check to make sure the gas key is tight. Good luck I have one of the gas block alignment tool on order and will use it once it arrives. I will check the gas rings, but need a better screw driver or take the Rainer BGC apart. |
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Quoted:
What buffer and spring are you using? Take a picture of the gas tube from the bottom of the upper receiver when it is separated. Your gas tube might be too short. There are several different "MLGS" AR10 gas tubes. If yours is short, it will produce the malfunction you are having. (I've been shooting and working on AR10s, SR25s, LR-308s for 13 years now, have owned and fixed many.) The gas tube extends about 11mm into the upper. The end is at the center of the circular cut in the upper. The gas key is 11.5 to 12 mm deep, so I assume the gas tube is ok. |
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Quoted: The gas tube extends about 11mm into the upper. The end is at the center of the circular cut in the upper. The gas key is 11.5 to 12 mm deep, so I assume the gas tube is ok. Quoted: Quoted: What buffer and spring are you using? Take a picture of the gas tube from the bottom of the upper receiver when it is separated. Your gas tube might be too short. There are several different "MLGS" AR10 gas tubes. If yours is short, it will produce the malfunction you are having. (I've been shooting and working on AR10s, SR25s, LR-308s for 13 years now, have owned and fixed many.) The gas tube extends about 11mm into the upper. The end is at the center of the circular cut in the upper. The gas key is 11.5 to 12 mm deep, so I assume the gas tube is ok. |
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I've had bad luck with stacking INtolerances on Rainier Arms ultra match everything. It's possible that the parts will wear in over time, it would take a good couple hundred rounds though. Beyond that, checking the gas tube and block alignment is correct. Check FRONT/BACK alignment and not just left/right. Most barrel makers place the gas port with the assumption of a handguard end cap in place which pushes it out a bit. In those cases if you have the gas block seated up against the shoulder you're a little too close in. -Stooxie |
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