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9/22/2017 12:11:25 AM
Posted: 9/11/2003 10:44:03 PM EDT
This is my third AR-15, but the first one I have built myself - well, the lower anyway. I bought a complete 20" DPMS 7.62X39 upper w/chromed carrier, bolt direct from DPMS. The lower: I bought a stripped RRA forged lower and a DPMS lower parts kit along with a DPMS A2 stock. Anyway, I got it all together without any problems. Everything functioned fine in the tests with the lower. I put the new DPMS upper on it and loaded a 7.62x39 snap cap into an AR-15 mag. I put the mag in the gun and pulled the charging handle. It chambered the round and I pulled the trigger - worked fine so far. I then pulled back on the charging handle and the round remained in the chamber/barrel as if the bolt didn't catch it to extract it and eject the shell. I tried this 3-4 times with the same results. Does anyone have any ideas? All the parts are brand new.
Link Posted: 9/11/2003 10:50:03 PM EDT
Headspace?
Link Posted: 9/11/2003 10:52:31 PM EDT
[Last Edit: 9/11/2003 11:07:55 PM EDT by jtb33]
That was my initial thought, but I assumed (my first error?) that since it was a prebuilt complete upper directly from DPMS, that they checked for headspace before the sent it out...
Link Posted: 9/11/2003 10:53:21 PM EDT
CORRECT bolt installed ?
Link Posted: 9/11/2003 10:55:36 PM EDT
Yes - correct bolt installed - that was one of the first things I checked.
Link Posted: 9/11/2003 10:56:13 PM EDT
My one suggestion with 7.62x39 AR's is Dont' go cheap on mags. THe best ones are frankenmags. Avoid the tapco cheapies liek the plague. Also, watch the bolt. Buddy of mine built a 7.62x39 upper. He was plagued with problems. Several problems turn up. The bolt was DPMS. the ejector was inserted backwards. This was done at the factory, as he purchased a complete bolt/carrier from DPMS. Second problem was shitty mags. I'd check the extractor. Pull the bolt out and try to stick a round in the face. See if it snaps in place, then come under spring tension (ejector test). IF it snaps into place, but doesn't want to jump out, Your ejector may be messed up.
Link Posted: 9/11/2003 11:04:26 PM EDT
Originally Posted By NAM: My one suggestion with 7.62x39 AR's is Dont' go cheap on mags. THe best ones are frankenmags. Avoid the tapco cheapies liek the plague. Also, watch the bolt. Buddy of mine built a 7.62x39 upper. He was plagued with problems. Several problems turn up. The bolt was DPMS. the ejector was inserted backwards. This was done at the factory, as he purchased a complete bolt/carrier from DPMS. Second problem was shitty mags. I'd check the extractor. Pull the bolt out and try to stick a round in the face. See if it snaps in place, then come under spring tension (ejector test). IF it snaps into place, but doesn't want to jump out, Your ejector may be messed up.
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Thanks - I checked that, and it does catch and then "want" to jump out (which is good I assume). Any idea where I can get "frankenmags" without making them myself?
Link Posted: 9/11/2003 11:05:28 PM EDT
[Last Edit: 9/11/2003 11:06:24 PM EDT by skullworks]
Originally Posted By jtb33: That was my initial thought, but I assumed (my first error) that since it was a prebuilt complete upper directly from DPMS, that they checked for headspace before the sent it out...
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So was it correctly headspaced? I've run into overspaced barrels before (non-AR, but still.) Don't see how mags would interfere in this case...
Link Posted: 9/11/2003 11:18:01 PM EDT
Originally Posted By skullworks: So was it correctly headspaced? I've run into overspaced barrels before (non-AR, but still.)
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How do I tell?
Link Posted: 9/11/2003 11:24:17 PM EDT
Originally Posted By jtb33: Any idea where I can get "frankenmags" without making them myself?
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Just FYI, I believe the "frankenmags" NAM was referring to are the USA brand mags that feature an AR-15 tower top attached to an AK-47 lower. Unlike the rest of USA brand totally worthless crap mags, these actually work, and work well. I got mine from CDNN, but I don't see them for sale in their catalog anymore. You need to find a company that sells USA mags to find these.
Link Posted: 9/11/2003 11:49:42 PM EDT
Originally Posted By jtb33:
Originally Posted By skullworks: So was it correctly headspaced? I've run into overspaced barrels before (non-AR, but still.)
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How do I tell?
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This is why God invented the headspace gauge.
Link Posted: 9/11/2003 11:56:17 PM EDT
[Last Edit: 9/11/2003 11:57:45 PM EDT by NAM]
Originally Posted By AK_Mike:
Originally Posted By jtb33: Any idea where I can get "frankenmags" without making them myself?
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Just FYI, I believe the "frankenmags" NAM was referring to are the USA brand mags that feature an AR-15 tower top attached to an AK-47 lower. Unlike the rest of USA brand totally worthless crap mags, these actually work, and work well. I got mine from CDNN, but I don't see them for sale in their catalog anymore. You need to find a company that sells USA mags to find these.
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Correct. I just happened to find mine at some podunk gun shop. They ar the only USA mag i will buy. THey actually work. my best suggestion is to keep an eye on the EE, and check online....ebay, gunbroker, etc. [img]http://pix.gunbroker.com/pixhost/2002-12-22/C.J.M._1040875488_Pc250069.jpg[/img] pic from gunbroker auction.
Link Posted: 9/12/2003 7:18:13 AM EDT
I appreciate all the help. I'll have it checked for headspacing problems and go from there. I put up an EE ad in the WTB for "frankenmags". Any idea what I *should* pay for one?
Link Posted: 9/12/2003 8:40:38 AM EDT
[Last Edit: 9/12/2003 8:45:22 AM EDT by Kaliburz]
Originally Posted By jtb33: I appreciate all the help. I'll have it checked for headspacing problems and go from there. I put up an EE ad in the WTB for "frankenmags". Any idea what I *should* pay for one?
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Well, a local gun dealer was clearing out his 20 round USA mags for $19.95...so I did my duty and cleaned him out. Eight mags worth... and this was just this July... [:D] Now, online, I've seen the 20 rounders going for about 35.00 and on auction, as high as 50 each. If its' the 30 rounders..... starting was like 45 last I looked. You also might find a drum for about 250-300.00 Edit- And the funny thing is, I have tons of mags, yet I have no upper!!! (yet)
Link Posted: 9/12/2003 9:40:04 AM EDT
I had the exact same problem with a olympic kit I built. The upper came assembled, i assembled the lower. To make a long story short, the problem was the extractor. I received a 5.56/.223 extractor in a 7.62 bolt. The difference between calibers in the bolt face is obvious. A 7.62 case will not seat in a 5.56/.223 bolt. The diffrence in the extractor is not as obvious. Other than the notch in the extractor which grabs the rim of the case it is identical.
Link Posted: 9/12/2003 9:50:01 AM EDT
Originally Posted By dws1057: I had the exact same problem with a olympic kit I built. The upper came assembled, i assembled the lower. To make a long story short, the problem was the extractor. I received a 5.56/.223 extractor in a 7.62 bolt. The difference between calibers in the bolt face is obvious. A 7.62 case will not seat in a 5.56/.223 bolt. The diffrence in the extractor is not as obvious. Other than the notch in the extractor which grabs the rim of the case it is identical.
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dws, Thanks for the info. I'll have to look at that when I get home.
Link Posted: 9/12/2003 10:04:39 AM EDT
[Last Edit: 9/12/2003 10:05:21 AM EDT by dogcatcher223]
I would call DPMS and talk to them, you will drive yourself crazy trying to figure it out. I would guess it is the bolt extractor. Have you tried a live round yet? I doubt those snap caps are spec.
Link Posted: 9/12/2003 10:22:41 AM EDT
That's a good point. No, I haven't tried it with a live round. Would that be safe as long as I only loaded 1 round in the magazine? Should I try removing the firing pin and reassemble the bolt/carrier (minus the firing pin) and try chambering a round and seeing if it will extract? Someone brought up the point about the snap caps - I just assumed it would be a good "tester" (even though that's not their purpose), since they worked fine in my AK's. If all else fails, I'll contact DPMS.
Link Posted: 9/12/2003 1:07:17 PM EDT
The gun is not going to go off unless the safety is off and the trigger is pulled. I fed a 30 shot clip of live ammo through mine manually to test function. Done it a lot. Just point the muzzle down at the floor or go to the range. Some will freak out and advise against it, but realistically nothing will happen. Just don't chamber a round and start waving the gun around. Real ammo is the only test for function. Running real ammo through mind via charging handle showed me one of my mags was bad. It would pop out two shells at a time.
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