The short stroke king (Please Help)

[Rhenerie]

Ok so here is the issue.

Just finished a 16" AR build. (ill put up a build thread once it works!)
Only stuff I can think of that matters
WOA 16" 1-7 Midlength barrel
M16 BCG
Syrac Ordnance Adjustable gas block
Rainier arms midlength gas tube.
DSG carbine buffer
Rainier buffer spring.

I am going to put the real big issue that is throwing me for a loop up first. Nothing appears to change when I adjust the gas block. . . . . . .

OK now to the information I have. I started the first round with the gas block as closed off as it gets, screw all the way in.
First rounds used. PMC 55gr FMJ. First round fired and successfully ejected. Bolt did not lock open.
Turned the gas block counter clockwise 180 degrees. Put one round in magazine. Successful ejection, failure to lock open.
Repeat
Repeat
Repeat
Repeat
Repeat
Repeat
Now the adjustment screw on the gas block has four threads hanging out Syrac's max. Successful ejection, failure to lock open.

So the main issue I have is how could there possibly be enough gas "Closed" to eject, and not enough "Open" to not lock open on empty ?

I did have 10 rounds of XM855 on hand, after the gas block was completely open and PMC was failing I tried them.

XM855 Ejected and locked open on empty.

Now I didn't try it when it was all the way closed but a couple times as I was opening up I tried two rounds of PMC in the mag. It always properly fed the second round.

I also had some hand loaded 52gr Amax on hand, they did eject but short stroked so bad as to not strip the next round.

Another individual at the range had some Federal walmart Bulk 55gr .223 It was able to lock open on empty on that.


I have since removed the gas block.
Alignment of the gas port was near perfect.
There was no bur or broken screw on the gas block.
Gas tube to gas block alignment was spot on.

The rifle started the day with a proper coating of frog lube + a bit extra because it was fresh. Ended the day in a bath of CLP and function was unchanged.




So I can easily understand how hotter loaded rounds enabled the rifle to function properly... What I cannot comprehend is how from fully closed to fully open on the gas system (Yes I verified after removal of gas block 4 threads out is past open) can have seemingly no affect on function...

I keep wanting to ask the question "Do I just have to feed this one really hot loads?" But I both don't like that it cant properly consume some factory loaded ammo and cant understand how it ejects while the gas system is under full obstruction by the gas block.... Note: The Syrac gas block cannot fully close of the gas system.. but it seems pretty close.

I'm at a loss here... Please help.

 

[Tflhnd1]

Still working on my expert status but it obviously is not getting enough gas back to to BCG, or what is "undergassed". A simple fix might be just slightly by slightly opening the gas port in the barrel. Others on here will better elaborate but Im pretty sure this is what is going on! Jeff

 

[rjacobs]

Why the adjustable gas block to begin with?

Possibly could go to an H buffer, which would increase dwell a tiny bit and possibly cause better function. It sounds opposite of what you would want to do, run something heavier, but some times, it keeps it locked up just slightly longer, allows the gas to act just a little bit more and bam, gun runs.

Also what mags? I have some magpul 20's that fail to lock back quite often.

 

[Rhenerie]

I tried colt 20 rounders and gen 2 pmags, same function.

The idea of the adjustable gasblock is I am trying to get this rifle to shoot as flat and with as little recoil as possible for 3 gun. It also has a muzzle break.

My assumption is that it is under gassed. I havent tried a heavier buffer. I see your logic here. . . I dont have any of the H buffers on hand.

I may try giving white oak a call tomorrow. I dont really want to open the gas port but I will if I have too. That was one of my concerns with the WOA barrel. I want to really narrow it down to the gas port first though

 

[BCP]

What does the gas port measure (as near as you can tell?)

 

[Rhenerie]

Based off the nearest drill that fits and the amount of wabble .079-.082ish

 

[Temp9]

This is interesting, as I'm having a nearly identical experience. Had a Syrac Gas Block with a carbine length tube and components, worked perfect four notches away from closed. I switched out to a rifle buffer (which has a much stiffer spring), and now the gun runs perfect except it doesn't fully lock back. The bolt catch locks on the bottom of the BCG as opposed to the front of the bolt.

I opened up the GB three turns, same exact thing. Another three turns, no change. Up until about one thread was showing, still no change. I opened it up as much as it will go, but haven't gotten to try it out fully opened yet. If it still doesn't work, a call to Syrac Ordnance is in order.

FYI, the barrel I'm using (Rainier UM, 16") is very overgassed thanks to an oversized gas port. The gun would dent brass to the point of being difficult to size when I was running a non-adjustable GB and a carbine buffer system.

 

[Rhenerie]

Under gassed guns with really heavy ejector springs will dent brass very badly as well, when the neck of the case smacks the barrel extension. This gun is doing that with the lighter loads. the XM855 comes out unscathed.

 

[Temp9]

Under gassed guns with really heavy ejector springs will dent brass very badly as well, when the neck of the case smacks the barrel extension. This gun is doing that with the lighter loads. the XM855 comes out unscathed.

My gun was denting cases on the body by ramming them against the shell deflector and bouncing them forward. I'm running a standard extractor spring with the black insert, no o-ring. 5.56 power loads. Installing the adjustable gas block fixed the issue. Cases ejected back to the 4:00 position with virtually no damage whatsoever.

After installing the heavier rifle length buffer system, though, it seems like I'm always short stroking slightly, regardless of gas setting.

 

[Jumper]

There is probably a restriction in the gas block because it sure sounds like your not getting enough gas. That, and nothing changes as you open it up. I've never seen or used a Syrac gas block so take it for what its worth but I would disassemble it as far as I could and inspect and clean. And if your are not getting enough gas, installing a stronger spring or heavier buffer is just going to make it worse.

 

[Mike_in_FL]

Ok so here is the issue.


Syrac Ordnance Adjustable gas block
I am going to put the real big issue that is throwing me for a loop up first. Nothing appears to change when I adjust the gas block. . . . . . .

OK now to the information I have. I started the first round with the gas block as closed off as it gets, screw all the way in.
First rounds used. PMC 55gr FMJ. First round fired and successfully ejected. Bolt did not lock open.

You just stated all of this, and you're thinking of opening up the gas port in the barrel already? I don't think checking the size of the port is a bad idea, but I think you've answered the question yourself. Particularly when you have someone saying they have this same gas block and a similar problem.

 

[Rhenerie]

You just stated all of this, and you're thinking of opening up the gas port in the barrel already? I don't think checking the size of the port is a bad idea, but I think you've answered the question yourself. Particularly when you have someone saying they have this same gas block and a similar problem.

I am only trying to narrow down the culprit.

I have removed the gas block inspected it and measured it. The gas block port is over .100 with zero leakage at the barrel. Very minimal leakage at the tube to gasblock junction. The gas tube has a port as large as the gas block. There is no obstruction, I can put string through the tube and out the gas block.

While it isnt entirely 100% ruled out, my current thought is the only potential issue is with the gas blocks ability to make major adjustments. Which I dont think is a predominant problem because I have used these blocks before. My thinking is that there simply isnt enough gas flow getting to the gasblock for its obstruction to be very meaningful..

I guess i could of been more specific. When I said there was no change, I ment in function of the rifle. There is a very short latter of brass marks on the shell deflector. Maybe 1/8th inch long finite brass drag lines indicating faster cycling as I opened the system. But after a certain point, mqybe half adjustment no change occured..

 

[Mike_in_FL]

I understand what you're saying. My experience has only been with the JP adjustable block. I don't think I would have much faith for one which would cycle the action when the gas should be blocked completely by the screw. Or am I somehow misreading your OP?

Is a Rainier buffer spring a one size fits all? Or is it intended for carbines? You've mentioned nothing about the lower, what kind of shape is the BHO in? Does it function with another upper correctly? Is the BCA new? Key bolts staked properly? No leaks there? New rings on the bolt?

 

[Rhenerie]

The syrac block isnt capable of completly sealing the gas path... JP blocks come darn close to being sealed when closed.

Lower functions properly. Fairly new. Seekins enhanced bolt catch. Very free pivoting.

I can look into the spring more but it was the same length/diameter/number of coils of another I have.

BCG is new. Proper staking. Tight gas rings. No leaks i can see.

 

[Rhenerie]

The only info on rainiers website is. Buffer spring for collaspable stocks m4/m16

 

[BCP]

Based off the nearest drill that fits and the amount of wabble .079-.082ish

That is about where it should be, 75-85.

I would think the gas block is wacky or you have a gas leak somewhere.

 

[tactserv]

I am going to go out on a limb and take a shot at this. Recoil spring too strong. A friend was building a bunch of ARs for customers and almost all of his guns had the same symptoms. In every case a quality spring (Colt, Spikes, etc) cured the problem. Seems the springs he got were simply too strong.

Fing a carbine that works and borrow the buffer and spring.

Good Luck, Mike

 

[Mike_in_FL]

A dumb question to ask at this point, but you can manually lock it back by hand and/or with the same magazine you have been using? Unless that gas block is completely out of whack, I'm going to guess that MAYBE they sent the wrong spring. They sell the rifle spring as well, maybe the wrong part was picked or put it the wrong bin. Standard rifle spring would be 12.75" long with 44 coils and carbine would be 11.25" with 39 coils. I would guess you got the 3.0 oz. buffer. It would seem to me you'd have a leak of epic proportions because I think you'd have plenty of gas with that port size. I'm not sure you could feel coil bind by hand cycling the rifle. If the lower worked before, but with a different stock/spring/buffer, could you swap another upper to test?

 

[archad]

PMC is weak .223 commercial spec ammo. Do not mess with gas port. Run better ammo.

 

[saint.308]

ooops I thought this thread was an old girlfriend trying to get my attention.


+1 on the H buffer. Before messing with the gas port.

 

[Rhenerie]

ooops I thought this thread was an old girlfriend trying to get my attention.


+1 on the H buffer. Before messing with the gas port.

Lol that was a good one.

Yes the rifle locks open on hotter loaded ammo. I'm thinking this is a PMC issue. Since posting I have ran across several references online of ARs with middy tubes or even carbine with full mass carriers not even cycling the stuff.. I was cycling it ok just not quite enough umph to get her to lock.. add to that ammo shortages and only 3 types of ammo to test with and not enough of any, I think better ammo and more breakin will have her shooting like a champ.

As a big FYI I did contact WOA about this. They answered the phone very promptly and were as helpful as they could be. John wasnt available to talk but I was told that I could send in my entire upper and they would inspect and test fire it free of charge. ((I only bought a barrel)) If any problema were found with the barrel replacement and rebuild would be free. If there was a build or component issue it would only be assemble fee plus parts.

I am thinking this is just an ammo issue. I will test this more and report back. I assumed pmc bronze 223 was average but i keep hearing its under powere.
One thing I didnt mention that goes along with this is going back to the rifle having a break. Both the federal walmart special and the XM855 were significantly louder and had less perceivable recoil....... The things you dont pay attention to when your frustrated...

 

[Rhenerie]

And I will try heavier buffers when I can. Wether I get this going as is or not.. I want it shooting flat and easy.

 

[Redcreek1]

How did you check the alignment of the gas port?

 

[Rhenerie]

By removing it and noting the carbon trace on the barrel.

 

[Som3 Dude]

Just finished a build with similar issues. Mechanically it was the exact same as two other rifles except for the adjustable gas system. Same barrels (14.5 mid system), BCG, buffer and spring. It was cycling enough to eject but not strip the next round and even this was intermitint. 4-5 shots perfect then 4-5 shots hanging up.

I though it was something faulty so I started putting parts out of other rifles into it to try but always the same problem. I came to the conclusion that the adjustable gas block at full open still inhibits a little gas flow. Borrowed a buffer spring that was the next lightest from a friend and it functioned perfectly (I went from a red topped to a blue topped spring). After that I went ahead and invested in the JP silent capture buffer system. Now it runs flawlessly and it is crazy soft shooting.

 

[Redcreek1]

By removing it and noting the carbon trace on the barrel.

On that barrel with that gas block the gas block should be about 1/32 of an inch out from the shoulder to properly line up with the gas port. if you have it all the way against the sholder then you are obscuring about half the gas port, so you will still have a carbon trace, but that wont telll you much. The White Oak barrel is set up for a standard front sight post and handguard with the metal spacer.

If you have a small machinist ruler (Starret or STi, etc) the thickness of the ruler itself is about right and you insert the ruler between the gas block and the shoulder on the barrel and then seat the gas block up against the ruler for proper spacing.

 

[Rhenerie]

Yes. You are correct. However the carbon trace is very defined and center over the port. I do have said gap. WOA dimples their barrels from the factory aswell so its kind of a no brainer.

 

[tylerw02]

I'm not saying it is the issue with yours, but until somebody asked, it sounded like a misaligned gas block or a gas block problem. I had the VERY same issue with an upper and come to find out the gas block wasn't initially aligned and gave identical symptoms. The rifle would function with spec 5.56 ammo, but short-stroked anything commercial. After pulling the block off and checking it out, it functioned fine.

My first suggestion would be that it is a gas block problem, perhaps something isn't quite Kosher---bad block maybe? But I'd also look at the gas key. Is it leaking? Is there an unusual wear pattern on the key? Are the gas rings in good shape? Those are the things to check first when something isn't right. If a gun doesn't function with standard buffers and with all ammo, there is something not right.