18" rifle length cycling issue

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18" rifle length cycling issue

Post by Niceguy » Fri Apr 28, 2017 1:21 pm

I have a 18" rifle length A2 style PSA kit and having issues picking up the next round after you shoot. When you rack the slide it picks the round up fine, but not the next round after you shoot it. All factory PSA parts. I tried a different bolt and CH and exact same thing. It scratches the hell out of the top of the round, but doesn't pick it up. Doesn't feed at all, fails 100% of the time. Opinions on what to try first? Maybe heavier or lighter buffer?

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Re: 18

Post by Gaffshot » Fri Apr 28, 2017 2:32 pm

After firing do you think the bolt is cycling all the way to the rear? Check gas block for alignment and make sure it is securely locked down directly over the gas port. Check gas tube. Check gas key. How far is the empty being thrown? If it is barely dribbling out of the gun then possible that gas system is leaking somewhere and causing the bolt not to be cycled fully to rear.

If bolt is cycling fully to the rear then try different mag. Try different upper on same lower. Try different lower on same upper.

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Re: 18

Post by Whootsinator » Fri Apr 28, 2017 3:01 pm

I second all of Gaffshot's recommendations, but I'd try swapping around uppers/lowers first. Easiest fix to hardest fix.
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Re: 18

Post by Gaffshot » Fri Apr 28, 2017 3:12 pm

Also consider what ammo is being used. Under powered ammo can cause this. I experienced this with some old Remington UMC yellow box 223.

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Re: 18" rifle length cycling issue

Post by Niceguy » Fri Apr 28, 2017 4:09 pm

I tried Freedom Munitions and Fed XM193, both acted the same. Also a GI and a Pmag. It launches the spent case pretty good, what I would consider normal. I don't have another rifle length buffer lower, would it be okay to try it on a lower with a carbine/middy buffer?

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Re: 18

Post by Whootsinator » Fri Apr 28, 2017 6:04 pm

Go for it. Not ideal, but nothing is going to blow up if it didn't blow up before. If the upper works on different lower, something to do with your lower is probably out of spec.
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Re: 18" rifle length cycling issue

Post by Niceguy » Fri Apr 28, 2017 6:37 pm

Whootsinator wrote:Go for it. Not ideal, but nothing is going to blow up if it didn't blow up before. If the upper works on different lower, something to do with your lower is probably out of spec.
It's an Anderson, so very possible...haha

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Re: 18" rifle length cycling issue

Post by iron369 » Fri Apr 28, 2017 8:40 pm

I would think putting the carbine lower on it would help tell if it's the dwell time. A rifle length gas system on an 18" barrel doesn't have enough dwell time to fully operate the rifle. From what I understand a rifle length gas system was meant for 20" barrels. Two inches shorter makes a lot of difference. (Ask most ladies about the difference 2" makes.)
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Re: 18

Post by Whootsinator » Fri Apr 28, 2017 9:03 pm

Rifle length gas systems are fine on 18" barrels, unless there's some crazy gas port sizing. 14.5" midlength is fine, even totally normal. Even a 12.5" midlength can be reliable, though it's not exactly common.
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Re: 18" rifle length cycling issue

Post by Niceguy » Fri Apr 28, 2017 9:27 pm

iron369 wrote:I would think putting the carbine lower on it would help tell if it's the dwell time. A rifle length gas system on an 18" barrel doesn't have enough dwell time to fully operate the rifle. From what I understand a rifle length gas system was meant for 20" barrels. Two inches shorter makes a lot of difference. (Ask most ladies about the difference 2" makes.)
It's a factory built PSA upper and their lpk, buffer tube, spring, and buffer that all came in the "18" A2 style rifle kit" together. I had another exact rifle I traded off a year or two ago and it functioned perfect and was surprisingly accurate for a cheap AR also. I've had awesome luck with PSA AR's and had TONS of them so I knew eventually I'd get one that was less that stellar...haha

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Re: 18" rifle length cycling issue

Post by iron369 » Fri Apr 28, 2017 9:31 pm

It could be as simple as it just needs more lube. Or the gas block is just seated 1/8" off. Idk. Since it's short stroking every round I thought the lighter carbine buffer might help
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18" rifle length cycling issue

Post by iron369 » Fri Apr 28, 2017 9:37 pm

Just like Anderson. They mass produce to keep prices low. Their percentage of errors are maybe a little higher than other companies but the sheer number of units with just an average error rate would produce more problematic units than some companies even produce annually.
People don't go nuts when their Anderson lower is out of spec. Let a Umbrella Corp lower be out of spec though.
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Re: 18" rifle length cycling issue

Post by Niceguy » Fri Apr 28, 2017 9:54 pm

I'll have to mess with it more this weekend and see what I can figure out. I'll try a carbine lower first and see how she goes.
Thanks everyone for all the possible things to look for.

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Re: 18

Post by Frailer » Fri Apr 28, 2017 10:45 pm

First thing I'd do is load a mag with one round. If the bolt locks open after firing, the gas system and buffer are probably fine.

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Re: 18" rifle length cycling issue

Post by Gunsmokin » Sat Apr 29, 2017 2:59 am

Frailer wrote:First thing I'd do is load a mag with one round. If the bolt locks open after firing, the gas system and buffer are probably fine.
This is what I was thinking. If it's under gassed, the bolt won't lock open.
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Re: 18

Post by Dave1965 » Sat Apr 29, 2017 7:32 am

open gas port ever so slightly until it works

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Re: 18" rifle length cycling issue

Post by Niceguy » Sat Apr 29, 2017 8:44 am

Cool, I'll try that also.

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Re: 18

Post by son of liberty » Sat Apr 29, 2017 9:49 am

Step one
Lube the piss out of the buffer tube and bolt. Cycle it by hand a whole bunch.

Step two
Load the weakest ammo you plan to run, wolf seems to work fine. Load one round and see if the bolt locks back on the empty mag.

Step three
If it dose not lock the bolt open, check the gas key on the bolt first, make sure its tight and well staked. Then check the gas rings in the bolt ( you are really just looking to make sure they have not broke and become lodged).

Step four
Decide your course of correction, buffer replacment, gas hole modification, buffer spring, or bolt change.
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Re: 18" rifle length cycling issue

Post by Niceguy » Sun Apr 30, 2017 9:57 pm

Alright, I had a chance to play a little more today... I lubed her up and cycled and dry fired for 5-10min. Same issue, she's a single shot AR...haha I was apparently smoking crack the last time I was shooting it because it only tosses brass about 2-3 feet out and never locked the bolt back. I swapped BCG and nothing changed. Swapped back to original BCG and swapped upped onto a carbine lower that I know functions perfect and the first 5-8 shots were single shots but shells went 8-10 feet ruffly. I loaded one at a time and it locked the bolt back every time. I loaded 5 rounds and it functioned perfect, loaded 5 more and perfect again, loaded 5 more and perfect again. Put it back on the original lower and still single shot, but now 4 out of 5 times charging it, you had to use the forward assist to get it to go the last 1/4" or so. When I get spare time again, I'll try a carbine upper on this lower and see what it does.

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Re: 18" rifle length cycling issue

Post by Niceguy » Sun Apr 30, 2017 9:58 pm

In the original configuration the bolt seems like it's moving in slomotion when you shoot it also. It feels normal charging it though...

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Re: 18

Post by Dave1965 » Mon May 01, 2017 7:43 am

haha

gas-- gas-- gas-- as they say in the army

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Re: 18

Post by Gaffshot » Mon May 01, 2017 11:46 am

I think I hear your saying that it worked fine when you put the upper onto a different lower and then it malfunctioned again when switched back to the Anderson lower. So safe to assume that the problem is likely related to the Anderson lower in some fashion (differential diagnosis). I once had a buffer tube get misaligned and threads stripped. Caused the tube to be out of alignment. Don't know how it happened. Unlikely occurence but it happened somehow. Check the buffer tube to make sure it is tight and properly aligned. Tighten the castle nut. Should be staked at some point when you fix the cycling problem.

Edit: Re-read your post and it looks like it also malfunctioned on the new lower. Looks like you're back to Gas Gas Gas. Gas block loose misaligned, cracked gas tube, loose gas key, improperly assembled.

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Re: 18" rifle length cycling issue

Post by Niceguy » Mon May 01, 2017 1:33 pm

First few shots on the known good lower it didn't cycle, but would lock the bolt back. The next 20 or so it functioned perfect on the good lower. Only the original fixed stock lower failed 100% of the shots, also wouldn't lock the bolt back, barely ejected the spent round, and had to use the forward assist every single time it was charged. I'm going with bad lower, be it the buffer or tube, or the lower itself being out of spec.

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Re: 18

Post by richief » Tue May 02, 2017 12:26 am

So it sounds like it cycled better on a carbine buffer but still not flawless, and won't cycle a rifle buffer at all. Do you have another upper to try on that rifle buffer lower? Probabbly short on gas I suspect, ehh? Maybe check for bent gas tube, using forward assist might be because gas tube misaligned with gas key. Also look around gas block for carbon leak and or remove gas block and see if carbon shows misaligned holes, also check diameter of barrel hole should be at least .063 min and prob more like .093, gas block can be bigger hole thats ok as long as centered over barrel hole.

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Re: 18" rifle length cycling issue

Post by Niceguy » Thu May 11, 2017 10:51 am

After the first 3-5rds on the carbine lower it cycled perfect, locked the bolt and acted just as it should. I put 20 or so more rounds through it last night on the carbine lower and still good to go. Tried 5 more rounds on the A2 lower, still single shot. I'm trying a new spring and buffer first and then if that doesn't work, I'll swap all pieces to a new stripped lower.

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