kit ar will not cycle first round

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12 years 2 months ago #12200 by tas1109
kit ar will not cycle first round was created by tas1109
I purchased a DPMS type rifle kit in 308 caliber from akpartskits.com. I have since changed the barrel to 260 remington. My problem is that the rifle does not seem to have enough force to strip a round from the clip, and chamber it. When I pull the charging handle back and release it, it strips a round from the clip, but does not have enough momentum to fully chamber the round. I have a DPMS 10 round mag, and a Magpul 20 round mag. It does it with both magazines.

I was wondering if the buffer and buffer spring might be the wrong ones?

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12 years 2 months ago - 12 years 2 months ago #12244 by sansone
Replied by sansone on topic Re: kit ar will not cycle first round
does the charging handle drag? Try charging with the bolt locking back, manually push the charg handle to the closed/locked position and tap the bolt release catch. Does it function correctly this way?
Make sure the buffer is not dragging due to a poorly installed extension tube. Also remember the spring is sometimes shorter for telescopic stock, If you have a fixed stock you may need the correct spring installed.
make sure the bolt locking lugs are rotating smoothly when closing the breech
Last edit: 12 years 2 months ago by sansone.

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12 years 2 months ago #12259 by LebbenB
Replied by LebbenB on topic Re: kit ar will not cycle first round
Did the problem also occur while the rifle was still chambered for .308?

Also check the feed ramps, there might be a burr or other obstruction that's hanging up the round.

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12 years 2 months ago #12265 by tas1109
Replied by tas1109 on topic Re: kit ar will not cycle first round
I finally got the rifle to function. It was a combination of several problems. First, I stretched the buffer spring a little to add more power. This solved the problem of chambering the first round using the charging handle.

Then I took it out to shoot, and it was not ejecting the spent round. The bolt would not pull the empty case from the chamber. When I pushed the case out with a rod it would come out easily. I figured that the dwell time was not right. I added weight to the buffer until it started ejecting.

Then I tried shooting the rifle using three rounds in the magazine. Up to this point I was loading one round at a time. Now the bolt would cycle back but it did not throw the empty case out of the upper receiver. So when the bolt would return to chamber the next round, the empty case would jam with the round the bolt was trying to chamber. I suspected the extractor, and the ejector. It seemed as though my ejector was about a 1/16 of an inch or so short. I made another ejector using the back end of a drill bit that was the correct diameter, and a dremel tool. This added more power to eject the spent case. Next I realized that the extractor was weak. It would not hold on to the fired case long enough to clear the receiver side wall, and eject the case. I also noticed that it did not fit into the bolt flush. So when the bolt would slide back into the bolt carrier, it would raise the front end of the extractor (end that holds the case). I took a file and did some filing on it until it fit flush with the bolt. Now the bolt carrier was not pushing on it causing it to lose hold of the fired case.

I took the rifle back out to the range today, and after a little adjustment on the gas block, the gun is running like a top. I got a good deal on this kit, and now I know why. I am sure that they are using seconds, or out of spec parts in these kits. Anyway, I am happy now, and I have learned a great deal about these rifles in the process.

Thanks, Everyone

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12 years 2 months ago #12266 by sansone
Replied by sansone on topic Re: kit ar will not cycle first round
I am glad you got it right but very disappointed that a company selling AR kits is marketing parts that need so much custom work when completed.

Best of luck to you and nice trouble-shooting work :P

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12 years 2 months ago #12270 by LebbenB
Replied by LebbenB on topic Re: kit ar will not cycle first round
Glad to read that you got your rifle running. However, pulling on the buffer spring is a band-aid fix at best. It sounds like you got an AR15 (.223/5.56) buffer and spring. You might want to try using an AR10 buffer/buffer spring. And I'd also buy a new bolt made by a reputable manufacturer like Armalite, LMT or LaRue.

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