DI experts- need your help

[bm11]

Ok, so here is the scoop. Yesterday, I picked up my new (to me) GAP AR-10 from my ffl where I had it transferred to. It is a 24" barrel .260 Remington, with a JP adjustable gas block. I mounted my scope last night, and took it to the range today.

I couldn't get it to cycle reliably to save my life. It seemed like it wasn't getting enough gas, because it was flipping the extracted round around but not really ejecting it, which was causing the next round to misfeed, and really messing up my brass. It would make sense that the block would have been tuned to the previous owners handloads, and the Black Hills I was running wasn't hot enough to get it to cycle.

Well, I didn't have an SAE toolkit with me, only metric, but I was able to borrow one and open the gas block adjustment up 2 full turns. It started to extract a bit better, so I opened it up another turn. It fed reliably for 5 rounds, so I brought the toolkit back.

Then, it started doing it again (the very next mag.) Every other round, maybe 60% of the rounds. Getting frustrated, I borrowed the toolkit again, and backed it out another turn. No better. I could hear the spring more, but no more reliable extraction. I backed it out another turn, no better. Fed up, I packed up and headed home.

So, what now? I have about $5k wrapped up in this not cycling piece of shit, and I am ready to throw it in the trash. Please help!

-Bob

 

[BigBoss0311]

Re: DI experts- need your help

Did you bother calling GAP yet?

 

[BigBoss0311]

Re: DI experts- need your help

Or if you really don't like your "non-cycling piece of shit", I will take it off your hands for the price of shipping.

 

[Falar]

Re: DI experts- need your help

I've never used a JP block before, but the other adj block only one I've seen actually REDUCED the gas that gets directed back into the tube when you opened it up and when you close the set screw it diverts more of the gas back into the action, bleeding off less of the excess. If this is the case with the JP block close it all the way and check for function then back it out little by little until it starts impacting function and then decide what you think is the sweet spot.

I'd recommend calling GAP or JP and find out how to adjust that gasblock properly.

 

[bburnham]

Re: DI experts- need your help

You ought to try replacing the ejector spring. A weak ejector spring that may look okay visually, may not be pushing the empty off the bolt face, as vigorously as needed. I had the same symptoms on new custom AR-10 that I put together. Turned out, the DPMS supplied bolt assembly had an AR-15 ejector spring. I had exactly the same issues you did. Once I put in the right spring, it hasnt missed a beat in several hundred rounds.
Over and under gas issues, buffer spring etc, all need be looked at, but if it "isnt ejecting" check the ejector first thing.

 

[bm11]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BigBoss0311</div><div class="ubbcode-body">Did you bother calling GAP yet? </div></div>Left a message, yes.

 

[PLeighton]

Re: DI experts- need your help

Sounds like the OP's GAP AR-10 is used.
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body"> Yesterday, I picked up my new (to me) GAP AR-10 from my ffl </div></div>
I would be careful when talking about GA Precision here.
Sounds like you are frustrated by the situation, not the company.
(There is a reason that most DI guns don't come with adjustable gas blocks.)

I would first follow the JP setup instructions for your gas block.
JP Adjustable Gas Block Manual
If you continue to experience the same problem:
- Inspect gas block to ensure that it is aligned properly.
- Check gas tube for wear.
- Check gas key on the bolt carrier to make sure that it hasn't come loose.
- Check gas rings for wear and alignment.
- Load a magazine with one round and see if you have the same issue.

Post the results and you will receive additional steps to follow.

 

[Falar]

Re: DI experts- need your help

With the link to the instructions it looks like my theory is out. The TS was using the block properly.

 

[bm11]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Dr. Phil</div><div class="ubbcode-body">
Sounds like you are frustrated by the situation, not the company.

</div></div>Yes, to clarify, I am frustrated by the situation and lack of my ability to find a solution. I am not frustrated by the seller (he is good to go) or the producer (GAP is good to go.)

 

[bm11]

Re: DI experts- need your help

Gas block

 

[bm11]

Re: DI experts- need your help

Bolt

 

[bm11]

Re: DI experts- need your help

Field strip:

 

[bm11]

Re: DI experts- need your help

inside of upper:

 

[bm11]

Re: DI experts- need your help

Other things of note- when hand cycling, it would eject the round exactly like you would suggest a hand cycled round to eject, which would suggest that the extractor and ejector springs are both OK.

When single feeding from a magazine, the round feeds fine, shoots fine, and the bolt gets enough energy to lock back, but I have to remove the round from the receiver by hand. It is usually sitting in backward at this point.

 

[PLeighton]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body">When single feeding from a magazine, the round feeds fine, shoots fine, and the bolt gets enough energy to lock back, but I have to remove the round from the receiver by hand. It is usually sitting in backward at this point. </div></div>Ding Ding Ding!!!
We have a winner!!!

The problem is going to be in either your ejector or extractor.
- Check to make sure that there aren't any obstructions in or around them.
- Check the extractor claw to make sure it is intact.
- Check the extractor spring and O-ring (if it has one) for proper tension.

Since the bolt is locking back on the single round without issue,
you have ruled out a gas issue as well as an action spring / buffer issue.

 

[salmonaxe]

Re: DI experts- need your help

Man. I can't remember exactly what it is, but there is a VERY distinct reason for brass flipping 180 in the AR platform. I saw a video of it recently and an explanation of the causes. Lemme see if I can dig it up.

I just remembered a detail! It's caused by increased carrier velocity. TOO MUCH GAS does this. Still can't find the video and thread about it. I swear it was a recent thread somewhere.

Wait! Here it is.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2043823

I could have sworn there was a video. I know I've seen a video before showing this in slowmo.

LOADS of problems happen to AR's if they're overgassed. Turning the gas up, just messes it up worse. I've noticed that a lot of AR-10 type rifles have this tuning issue. Especially if one uses a carbine buffer. (I opted for use of the AR-10 specific "longer" carbine buffer and tube tube since it seems to have a better track record than a lot of other carbine buffers, with AR-15 length carbine buffer tubes.)

 

[bm11]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Salmonaxe</div><div class="ubbcode-body">
I just remembered a detail! It's caused by increased carrier velocity. TOO MUCH GAS does this. Still can't find the video and thread about it. I swear it was a recent thread somewhere.
</div></div>Salmonaxe got it right. <span style="font-weight: bold">PROBLEM SOLVED</span> I actually went back to the range a few hours ago, and while this post hadn't popped up yet, I figured it was the only thing left to try. Turned it in 2 full turns, it started popping them out the side about 4 inches. Went another full turn, and BAM, perfect 4" ejection into a neat little pile!

Thanks for all the help guys!

-Bob

 

[salmonaxe]

Re: DI experts- need your help

Glad you got it sorted out. +1 internets for me.

 

[bm11]

Re: DI experts- need your help

So am I. I was going to lose sleep over this, until I could get back to the range, which would have been another week or so! The last 30 rounds all ejected perfectly, so I think it is safe to say that the problem is now solved.

 

[bm11]

Re: DI experts- need your help

Picture of what it was doing:

 

[salmonaxe]

Re: DI experts- need your help

I wish I could find the video I saw. It was pretty interesting. It did something like flip out and then bounce right back in.

Did your brass end up with some pretty big dents in the side of the case?

 

[bm11]

Re: DI experts- need your help

Um, not too bad. The worst though was that if it had a loaded round behind it- it would fuck up the round going in, and the case of the ejected (not so much) round.

 

[rcw3]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Salmonaxe</div><div class="ubbcode-body">
I just remembered a detail! It's caused by increased carrier velocity. TOO MUCH GAS does this. Still can't find the video and thread about it. I swear it was a recent thread somewhere.
</div></div>Salmonaxe got it right. <span style="font-weight: bold">PROBLEM SOLVED</span> I actually went back to the range a few hours ago, and while this post hadn't popped up yet, I figured it was the only thing left to try. Turned it in 2 full turns, it started popping them out the side about 4 inches. Went another full turn, and BAM, perfect 4" ejection into a neat little pile!

Thanks for all the help guys!

-Bob </div></div>

FWIW - I hate to say this, but if your cases are only ejecting 4" from the gun your problem is certainly not solved by any means, and all that has occurred is that by tinkering with the gas system you have found a narrow "window" where you could get fired brass out of the gun for now. Case ejection should be positive and definitive and 4" from the gun means to me it's on the boarder of the cases just falling out of the rifle. If it were me, I would swap out the extractor with a different one and try it and see what happens, as it seems to me your extractor may be letting go of the case prematurely and the cases are just barely falling out of the rifle instead of being pushed definitively clear of the rifle.

Another option is the extractor is holding onto the cases and won''t let go - seen that one before - either way I would try out a different extractor.

Robert Whitley

 

[shane45]

Re: DI experts- need your help

I am sure it is a gas issue, not an extractor issue.

 

[Redmanss]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rcw3</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bm11</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Salmonaxe</div><div class="ubbcode-body">
I just remembered a detail! It's caused by increased carrier velocity. TOO MUCH GAS does this. Still can't find the video and thread about it. I swear it was a recent thread somewhere.
</div></div>Salmonaxe got it right. <span style="font-weight: bold">PROBLEM SOLVED</span> I actually went back to the range a few hours ago, and while this post hadn't popped up yet, I figured it was the only thing left to try. Turned it in 2 full turns, it started popping them out the side about 4 inches. Went another full turn, and BAM, perfect 4" ejection into a neat little pile!

Thanks for all the help guys!

-Bob </div></div>

FWIW - I hate to say this, but if your cases are only ejecting 4" from the gun your problem is certainly not solved by any means, and all that has occurred is that by tinkering with the gas system you have found a narrow "window" where you could get fired brass out of the gun for now. Case ejection should be positive and definitive and 4" from the gun means to me it's on the boarder of the cases just falling out of the rifle. If it were me, I would swap out the extractor with a different one and try it and see what happens, as it seems to me your extractor may be letting go of the case prematurely and the cases are just barely falling out of the rifle instead of being pushed definitively clear of the rifle.

Another option is the extractor is holding onto the cases and won''t let go - seen that one before - either way I would try out a different extractor.

Robert Whitley</div></div> I think that is just a typo on the shift key, and he meant 4' (ft) for the final ejection, but I'm sure he'll clarify it tomorrow.

 

[bm11]

Re: DI experts- need your help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Redmanss</div><div class="ubbcode-body"> I think that is just a typo on the shift key, and he meant 4' (ft) for the final ejection, but I'm sure he'll clarify it tomorrow. </div></div>Yes, 4 feet, it was a typo!