Help Me Please . my new 18" bbl rifle length gas system AR15 223 WILL NOT "RUN"

charliebrown1999

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I took it to the indoor range 1 hour ago and the new 18" bbl with rifle gas system and pinned gas block with muzzle break installed by me. It is a great "single shot" AR. It will extract and eject the spent casing but it will not strip and load a new round from the magazine. I have tried the factory Springfield Armory Saint Heavy Tungsten buffer which is marked "H", and I have tried a new Del-ton carbine length buffer which is unmarked. I do not know the weight of either of these buffer as my powder scale only measures grains. So I need the bright minds of all you AR experts solve this problem.
 

BurnOut

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May not have enough barrel after the gas port. As I recall, most 18" barrels run a mid-length gas system for this reason.

I'm not saying that that's definitely what's going on, but you may end up needing to run a lighter than normal buffer/spring.

Another test to run... if you load a single round in the mag and fire it, will it lock back on the empty mag?
 

charliebrown1999

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FN CHF CHROME LINED CAL 223 WYLDE . PINN.ED GAS BLOCK I D o NOT KNOW THE THE MAKE. ammo all 55gr fmj PMC. XM193 556 FEDERA; AND WOLF GOLD. am I screwed?
 

charliebrown1999

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May not have enough barrel after the gas port. As I recall, most 18" barrels run a mid-length gas system for this reason.

I'm not saying that that's definitely what's going on, but you may end up needing to run a lighter than normal buffer/spring.

Another test to run... if you load a single round in the mag and fire it, will it lock back on the empty mag?
yes the single round test was the first one I ran and it did pass. I will try to weigh the del-ton carbine buffer. that could be the
the problem
 

loveha

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Any tiny set screws on the gas block?anything to indicate it's adjustable?

Pictures would help a whole lot.

Could need breaking in. To much pressure on a full mag if it locks back on one round in.
 

hafejd30

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Is this built by you or the PSA complete upper your referring to on your other thread?
 

BurnOut

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yes the single round test was the first one I ran and it did pass. I will try to weigh the del-ton carbine buffer. that could be the
the problem
Hmmm. Sounds like it's right on the edge... if it was me, I think I'd try a standard weight buffer next.
 

TonyTheTiger

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Dump all the weights out of your buffer and see if it runs all the sudden. If it does you're undergassed. You sound undergassed but I have seen rifles so severely overgassed that the bcg outruns the mag spring, so you can actually get similar symptoms at opposite ends of the spectrum. It's unlikely thats the problem with an 18" rlgs though.
 
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TonyTheTiger

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May not have enough barrel after the gas port. As I recall, most 18" barrels run a mid-length gas system for this reason.
Maybe 10+ years ago but rifle gas 18" barrels are very well sorted these days, to the point that 16" rlgs barrels are becoming more common. I know 60+ people with 18" barrels, and there isn't a mid length among them.
 

hafejd30

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Does sound like lightening up your buffer may do the trick as suggested above

A lighter weight bolt carrier may help to

Try different mags if you haven’t already as well
 

MontanaMan

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Well, you can try to call PSA & try to get them to tell you what buffer weight & spring weight they recommend or just send it back to them.

A carbine buffer is 3 oz & you should start there with a standard weight spring (Sprinco white).

Sprinco also makes a reduced power (yellow) spring & I would try that as well.

As Tony says, you could take the weights out of your buffer for a test but there are lighter weight buffers available as well as adjustable weight buffers than can get you well below a 3 oz. carbine weight.

As a last resort, you could also try a lighter weight BCG.............those are normally used with an adjustable gas block, so since it does not sound like yours is adjustable, you would then have to optimize the buffer & spring weight with more testing.

Also, maybe try a hotter genuine 5.56 NATO ammo like IMI.

If you really don't understand how all of the above works together, & aren't willing to dink with it, I'd just send it back to PSA.

Good Luck

MM
 

BurnOut

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Maybe 10+ years ago but rifle gas 18" barrels are very well sorted these days, to the point that 16" rlgs barrels are becoming more common. I know 60+ people with 18" barrels, and there isn't a mid length among them.
Well, today I learned something. 'tis true that my knowledge on this is dated to the era that you mentioned (not to mention my own RRA 18"/mid-length setup).
 

benchmstr

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Get a JP flat wire spring...most of the AR problems stem from a shitty spring...but people are too quick to open up gas ports and get adjustable gas blocks instead of figuring it out..

Most springs are terrible

Bench
 

Jsp556

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Run nato pressure ammo and you should be good. 18” rlgs rifles are probably my favorite set up.

My Brother in law built a 16” middy and it will not run on cheap, low pressure, dirt clod ammo.

This is why most companies put giant gas ports in their barrels and why crutches such as adjustable gas blocks exist.
 

MSTN

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The rifle length gas system is ideal for an 18" with a wild chamber, assuming:

1. You're running quality ammo.

2. You're using quality magazines.

3. The gun is sufficiently lubed.

4. Nothing else is FUBAR.
 
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TonyTheTiger

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and why crutches such as adjustable gas blocks exist.
I don't know if I'd go as far as to label them crutches. Besides the barrel manufacturer having no way of knowing which of the endless possibilities of parts combos you may be running, they are helpful for people that regularly change components or tweak loads. And then there's the guys like me that have set ups that are so far off the beaten path that the ideal barrel doesn't exist so its easier to just turn a screw to balance things out.
 

Precision Underground

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I don't know if I'd go as far as to label them crutches. Besides the barrel manufacturer having no way of knowing which of the endless possibilities of parts combos you may be running, they are helpful for people that regularly change components or tweak loads. And then there's the guys like me that have set ups that are so far off the beaten path that the ideal barrel doesn't exist so its easier to just turn a screw to balance things out.
Yep. And once you tune a rifle with the right springs, buffer, and gas level.... you will shoot it once and never want to shoot one again that isn’t perfectly tuned.
 

charliebrown1999

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will try the yellow spring. will try to weigh buffer and buffer weights and reduce .5 oz.
Get a JP flat wire spring...most of the AR problems stem from a shitty spring...but people are too quick to open up gas ports and get adjustable gas blocks instead of figuring it out..

Most springs are terrible

Bench
Thank you - will do.
 

shax2lex

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I wouldn’t consider adjustable gas blocks as crutches. Everyone’s set up is different and all ammo is different. It’s nice to turn the rifle to the ammo.
 

RyanScott

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I should have written more clearly. If the spring meets the spec and you’re using an H buffer the gun will work or something other l than the buffer or spring is wrong. You don’t need a flat or braided wire spring. Just shit can them when they are less than 10” relaxed.
 

TonyTheTiger

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Yep. And once you tune a rifle with the right springs, buffer, and gas level.... you will shoot it once and never want to shoot one again that isn’t perfectly tuned.
True story. I did a little tinkering in the rain today, check out the lack of muzzle rise or recoil and note that I'm pretty much free recoiling the rifle, not leaning into it or pulling hard rearward.


It's insane how a well tuned rifle feels and how little dispersion you can get. The target I was shooting at 20 yards:
20190921_163123.jpg
All easily in the A zone even with the triples thrown in.
 

Precision Underground

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True story. I did a little tinkering in the rain today, check out the lack of muzzle rise or recoil and note that I'm pretty much free recoiling the rifle, not leaning into it or pulling hard rearward.


It's insane how a well tuned rifle feels and how little dispersion you can get. The target I was shooting at 20 yards:
View attachment 7151065
All easily in the A zone even with the triples thrown in.
Is that an echo trigger or does it have the fun setting on it?!!
 

hafejd30

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I have an upper that’s tuned with a standard carrier and adjustable gas block. Never realized how smooth an AR 15 could run. All my other AR are the full auto BCG with non adjustable gas blocks. Noticeable amount of recoil difference. The gun operates very smooth.

Turning that into a suppressed MK12 platform currently. Will be switching to a full auto BCG with a Saker 556. Hoping to smooth it out a bit
 

Broncovan

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I took it to the indoor range 1 hour ago and the new 18" bbl with rifle gas system and pinned gas block with muzzle break installed by me. It is a great "single shot" AR. It will extract and eject the spent casing but it will not strip and load a new round from the magazine. I have tried the factory Springfield Armory Saint Heavy Tungsten buffer which is marked "H", and I have tried a new Del-ton carbine length buffer which is unmarked. I do not know the weight of either of these buffer as my powder scale only measures grains. So I need the bright minds of all you AR experts solve this problem.
I have that same barrel, had the same problem. I was trying to get it tuned up for a 3gun rig and like you, it was a single shot. Low mass BCG, adjustable gas block, lightened buffer. I had the gas block adjusted all the way out so I thought that was the problem. Fortunately, the manufacturer of the gas block is local so I took it to them to check out, they dropped a pin down the gas port in the barrel and guess what, it wasn't drilled all the way through. They drilled it through and I've never had another problem with the gun.
Get a drill bit and make sure it drops all the way through the port.
 

ShooterwithNoName

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Pretty smooth shooting rig Tony, just a little tuning goes a long way. So does a good trigger to making those doubles and triples actually hit the zone... and a lot of practice.

OP, when your rifle fires that one single round... Do you remember where the brass was landing? If it's slinging the brass forward or straight beside you it's probably undergassed. If it's slinging that one piece of brass like straight behind you at 6 o'clock then it's way over.

Check your BCG group too... Make sure your gas key is tight, not hanging up on the gas tube, gas tube maybe bent, deformed, etc... I bought a PSA lower that came from PSA doing something similar. They cranked the hell out of the buffer tube castle nut and actually caused the BCG to bind up as it went back in the buffer tube.

Good luck....
 

charliebrown1999

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I have that same barrel, had the same problem. I was trying to get it tuned up for a 3gun rig and like you, it was a single shot. Low mass BCG, adjustable gas block, lightened buffer. I had the gas block adjusted all the way out so I thought that was the problem. Fortunately, the manufacturer of the gas block is local so I took it to them to check out, they dropped a pin down the gas port in the barrel and guess what, it wasn't drilled all the way through. They drilled it through and I've never had another problem with the gun.
Get a drill bit and make sure it drops all the way through the port.
I have that same barrel, had the same problem. I was trying to get it tuned up for a 3gun rig and like you, it was a single shot. Low mass BCG, adjustable gas block, lightened buffer. I had the gas block adjusted all the way out so I thought that was the problem. Fortunately, the manufacturer of the gas block is local so I took it to them to check out, they dropped a pin down the gas port in the barrel and guess what, it wasn't drilled all the way through. They drilled it through and I've never had another problem with the gun.
Get a drill bit and make sure it drops all the way through the port.
Thank you for the advice. Problem solved with springco Yellow reduced spring.