I am at my wit's end. First AR build, can't get it to cycle properly. Hoping for some advice.

Jay Ell Gee

New member
Hey everyone. Early last year, I put together my first AR. It consists of an 18" 223 wylde rifle length upper with 15" handguard (PSA complete upper) with a BRT linear comp. I am running a PSA carpenter steel BCG. Spikes lower, RRA LPK, RRA NM trigger, as well as a magpul STR stock. Standard carbine spring/buffer setup. I am using Magpul 10 round magazines.

While I have had this rifle built for about a year, I have only managed a handful of outings, due to a new job (lots of OT for training) and planning a wedding. Now that the wedding and deer season have come and gone, I'm back to fighting with this rifle.

The rifle will typically do one of two things. It will either "short stroke" and not chamber a new round (not as common), or the bolt will actually drag a round from the magazine up into the feed ramp area, catching the brass not far below the shoulder (more common). I cannot simply drop the magazine to clear the jam, as the loaded round will still be halfway in the magazine. This binds the magazine up until I can lock the bolt back, clear the round from the magazine, drop the magazine, and then the round obviously falls free, effectively ruined. The bolt will usually not lock back on the last round, though it does happen occasionally.

I have done literally everything possible to get this thing to function, including a visit to a gunsmith. They could not reproduce the issue, even when I left one of my magazines with them.

I have tried the following things to get the gun to cycle...

Removed rail and gas block (smith also did). Alignment is fine.
Gas port measures .094
Swapped lowers with two friends. One was a bone stock S&W factory lower.
Purchased a new RRA carbine buffer spring.
Used all kinds of ammunition. Red box black hills, creedmoor sports match ammo, 5.56 black hills, fiocchi 223, probably more that I can't remember.
Tried two different magazines.
Gas rings passed the "stand the BCG on the bolt" test.
Rifle cleaned and lubricated generously every trip.

At this point, I am effectively baffled. I called PSA, and after discussing every possible fix that I could try, they said that they would take a look at the upper. That's all fine and good, but the upper shoots very well and I hate to risk it spending weeks on end with them with pretty much no updates, as I have found their customer service somewhat lacking. I would rather address it myself, if possible.

Thanks in advance for anyone that takes the time to read this and provide suggestions. I'm just about to sell this dang thing and buy a bolt gun.

Joshua


 
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When no one else can replicate the malfunction it's time to look at other reasons...I would take this thing some place where you can shoot it with the butt against a tree or metal pole in the ground or some other solid non-moving object and with known good ammo fire it. Just like a pistol, you can "interrupt" the cycling by riding it back and "taking" the recoil. Just as you have to lock your wrist so a 1911 will cycle you also can "ride the recoil" back with an AR. It's an easy thign to do and those that do it most of the time don't even realize they are and so refuse to believe it.
Second thing is ammo...was the same ammo used when the folks that "couldn't replicate" tested it??? There is a lot of different ammo available out there for AR's and most of it is fine, but because there is so much there is also always the possibility that some is not so good.
Next is gas system...find someone that has a borescope and have them verify that the port and gas block align. This is best done with a borescope. Then I would run wire and spray cleaner thru the gas tube...I have found junk in brand new gas tubes that stopped cycling. If the bolt moves properly in the carrier and the rings are in place and the key is tight then I would suspect the receivers themselves. Sometimes they get machined wrong and there is too much tension between the bolt carrier and the rounds in the magazine. I have seen the buffer tube thread drilled crooked and the buffer drags in the tube.
At this point, about the only other thing it could be is a miss-adjusted adjustable gas block. If all of the above checks out good then suspect the action spring. Cut coils one by one it until the gun works or get a new spring.
 
It sounds like your not getting enough gas pressure; or not getting pressure for a long enough duration (18" barrel with rifle length gas)

Where is the brass ejecting?

Will bolt hold open on last round?
 
Like I mentioned in my original post, the bolt only stays open on the last round occasionally, but not very often. It's definitely not consistent, but more often than not, it will not lock back.

I've actually been through that Troubleshooting list, thank you. I've tried everything I can, including borrowing an h2 buffer, which didn't help a bit.

I'm going to try some 5.56 ball ammo this week to check cycling. I'll try to make it a point to note brass ejection angles then. I've never really paid attention to that. Thanks.
 
I bet your gas block isn't installed correctly. That's where 90% of those problems start. Edit: gotcha, cleaning gets done.
 
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With the failing to lockback and cycle it sounds like a gas issue. We have had the same problem with 18in Wylde's running rifle gas systems, just not enough barrel to keep the pressure there long enough. Sadly, I am not sure you should attempt to open the port as this would void any warranty you might have.

You might also look at installing a improved extractor spring. I have seen some rifles/carbines appear to short stroke if they are not shouldered tightly enough. Check and see if your extractor has an o-ring. If it does try putting a sprinco upgraded spring in it. This seems to be possible since the gunsmiths couldn't replicate the problem and a gas system issue should have shown up for the gunsmiths.
 
Originally Posted By: SnowmanMoWith the failing to lockback and cycle it sounds like a gas issue. We have had the same problem with 18in Wylde's running rifle gas systems, just not enough barrel to keep the pressure there long enough. Sadly, I am not sure you should attempt to open the port afs this would void any warranty you might have.

I agree. I'd send it back and let the supplier deal with it. This combination can be problematic. I've had guys basically call me a scum sucking pig over this problem because "all" the 3Gun guys run the RLG on an 18" with no problems. Well having done a little competition in that area you don't bring a gun that doesn't run to a match. There's a lot of drilling and spring balancing when you run the ragged of dwell time reliability.

Greg
 
I'd say you're not getting enough gas. Rifle length gas systems on 18" barrels don't have much dwell time, after the bullet passes the gas port. Generally speaking, they will function better with full-powered 5.56 Nato ammo. When it comes to ammo, I roll my own, so I can't really make a recommendation but, if you can find some hotter 5.56 factory loads, you might solve the problem. Using hotter 5.56 loads can be helpful, especially while breaking in a new rifle. Out of the box, things have a pretty tight fit, and it can take a little more oomph to make that cycle happen reliably.

If the problem persists, the next thing I'd check would be the gas block alignment. As mentioned, that's where a lot of these issues come from on a new build. If the gas system is all properly aligned and you have no leaks, enlarging the gas port is your last resort. If it actually came down to re-sizing the gas port, I'd be tempted to swap that barrel for one with a mid-length gas system. If you're not doing any competition shooting, you'd probably be a lot happier with the added reliability of a bit more gas pressure. The one thing I don't have much patience for is a rifle that's finicky about ammo.

I've seen PSA advertising a lot of those 18" rifle-length rigs. It's always surprised me, since that configuration is something the competition shooters seem to prefer, and it usually takes a lot more tuning and tinkering to make it 100% reliable.
 
Just a thought. You said the smith checked the alignment of the block and it was ok. What about the alignment of the tube to the block. Or the tube itself. With a 96 thou hole it ought to work with anything.
 
Originally Posted By: MGYSGTJust a thought. You said the smith checked the alignment of the block and it was ok. What about the alignment of the tube to the block. Or the tube itself. With a 96 thou hole it ought to work with anything.

+1 I was thinking of a possibly obstructed gas tube.

Additionally, to the OP, have you tried the tilt test with just the BCG in the upper? Turn your upper upside down, remove the CH, pull out the BCG and then tilt the upper at 45 degrees towards the barrel end. BCG should slide unobstructed.

I had the exact issue you describe. With my instance, the buffer spring was too long, got a defective one and never thought to look.
 
I agree with all the above, probably a gas problem. That being said, I've had plenty of problems with P mags or plastic mags. Try a metal feed lipped mag like Lancer or ASC. Plus I'd try running the bolt wet with a high quality lube & lightly lube the buffer spring. I've always used the plastic gas tube alignment pins from HB Industries & never had one miss aligned. Drop correct size pin in gas port hole, put on gas block, turn barrel over & over until pin drops in the barrel & out freely, tighten gb & use a cleaning rod to push out both parts on the orange plastic pin. Perfect alignment. Just my 2 cents worth.
Jim D
 
Heretic, I tried your tilt test. Good to go. Most of the other suggestions are, unfortunately, things that I have already stated as done in previous testing.

When I purchased my magpul STR stock, it came in a "kit" with a buffer tube, carbine buffer, as well as a carbine spring. I decided to pick up a new spring recently (RRA factory new) and it was dang near a half inch longer than the one included with my kit. I ran about twenty rounds through it last trip and it jammed twice.

I'm hitting the range tomorrow after work. I have some standard 5.56 FMJ to try, as well as a few boxes of fiocchi 223 (which I have been told is pretty hot) to work through the gun. Hoping to put about 150 rounds through to see what's going on.

I also borrowed a coworkers complete lower, which he says functions 100%. It's a long shot, but I'm going to even try it on a very well broken in lower. He also loaned me a few mags to try.

As to ejection angle, my wife shot next to me on our last trip. To her recollection, ejection angle was about 4:30.

I'll update here tomorrow. If this thing doesn't start shooting well tomorrow, it's going back to PSA. I already have a prepaid shipping label in my email inbox.

Thanks for all of the input, everyone.
 
I just re-read the original post, and saw the trigger is a RRA NM. This is totally outside the normal thinking but it happened to me so it's worth looking at. I had a 25 wssm Dtech not functioning correctly and after a lot of head scratching Mike asked what trigger I had. When I said RRA he said aha! He had me measure the clearance between the top of the hammer when it's pushed all the way down, and the bottom of the bcg. Mine only had a few thou clearance which caused excessive drag. Taking the top corner of the hammer down a bit cured it. I can't remember the exact clearance he recommended but it seems like at least 20 thou or so. After that I checked the rest of mine and had another that was pretty close so I fixed it also.

If it works with your buddy's lower then it's definitely something to consider.
 
Originally Posted By: 204 ARI just re-read the original post, and saw the trigger is a RRA NM. This is totally outside the normal thinking but it happened to me so it's worth looking at. I had a 25 wssm Dtech not functioning correctly and after a lot of head scratching Mike asked what trigger I had. When I said RRA he said aha! He had me measure the clearance between the top of the hammer when it's pushed all the way down, and the bottom of the bcg. Mine only had a few thou clearance which caused excessive drag. Taking the top corner of the hammer down a bit cured it. I can't remember the exact clearance he recommended but it seems like at least 20 thou or so. After that I checked the rest of mine and had another that was pretty close so I fixed it also.

If it works with your buddy's lower then it's definitely something to consider.

Never in a million years would I have considered something like that an issue. While I am not exactly qualified to do something like that myself, I will definitely keep it in mind.

Thanks!
 
Originally Posted By: Jay Ell GeeHeretic, I tried your tilt test. Good to go. Most of the other suggestions are, unfortunately, things that I have already stated as done in previous testing.

When I purchased my magpul STR stock, it came in a "kit" with a buffer tube, carbine buffer, as well as a carbine spring. I decided to pick up a new spring recently (RRA factory new) and it was dang near a half inch longer than the one included with my kit. I ran about twenty rounds through it last trip and it jammed twice.

I'm hitting the range tomorrow after work. I have some standard 5.56 FMJ to try, as well as a few boxes of fiocchi 223 (which I have been told is pretty hot) to work through the gun. Hoping to put about 150 rounds through to see what's going on.

I also borrowed a coworkers complete lower, which he says functions 100%. It's a long shot, but I'm going to even try it on a very well broken in lower. He also loaned me a few mags to try.

As to ejection angle, my wife shot next to me on our last trip. To her recollection, ejection angle was about 4:30.

I'll update here tomorrow. If this thing doesn't start shooting well tomorrow, it's going back to PSA. I already have a prepaid shipping label in my email inbox.

Thanks for all of the input, everyone.

FYI, a carbine spring should measure between 10 1/16" minimum to 11 1/4" max with 37-39 coils.

A Rifle spring should be 11 3/4" to 13 1/2" with 41-43 coils.
 
Carbine spring checks out fine against those measurements. Thank you.

Went to the range this evening. Ejection was fairly weak, roughly 60% the distance of another gentleman with an AR. Ejection was pretty consistent in the 4:30 direction.

Tested 5 mags and 2 lowers.

5.56 ammo cycled the bolt with no issues, but would still not lock the bolt back on the last shot.

Swap to 223, and short strokes all day. The bolt would almost never pick up another round from the magazine. Bang, click. No lockback there, either. Shocking.

I'm just about out of ideas. PSA is asking for both the upper and BCG to go over them and check them out. I have a prepaid shipping label in my inbox. Looks like it's heading back to PSA.

Thanks for everyone's input. I have a lot of money down the drain on this build. Hopefully PSA can figure something out.
 
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