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1/16/2020 9:48:49 PM
Posted: 1/1/2007 8:55:26 AM EST
Hello everyone, happy new year. Well, in part of my celebrations on New Year's Eve, I went down to the range to do some blasting. I was testing out my new Sabre Defence barreled upper from PK Firearms. But much to my dismay, I discovered some interesting problems.

I started firing with Winchester Q3131 ammo. Fired off one shot. Fired flawlessly, the case was extracted. When I attempted to fire the second round, CLICK. I looked through the ejection port and noticed the bolt didn't lock all the way forward. It was closed, but not locked. It also didn't feed the next round. So I charged it, and fired off the second round. Same thing; bolt didn't lock completely forward and FTF.

I thought it was my magazine maybe, so I switched magazines. Same problem. Tried those magazines in my Bushy M4gery, and they worked flawlessly. Then I tried Lake City M855 ammo. That cycled the weapon properly, and I had no isses with the M855 ammo in the 20" Sabre Defence barreled upper. I thought that was very strange.

Anyone have any idea what might be causing this problem? Is the Q3131 underpowered and causing my rifle to not cycle properly?
Link Posted: 1/1/2007 9:01:47 AM EST
Maybe your rifle just needs some break in.
Link Posted: 1/1/2007 9:04:18 AM EST
Clean it, lube it, shoot it.

After 200-300 rounds see if it still has a problem.
Link Posted: 1/1/2007 9:05:49 AM EST

Originally Posted By LoneWolfUSMC:
Clean it, lube it, shoot it.

After 200-300 rounds see if it still has a problem.


+1 Break it in.
Link Posted: 1/1/2007 9:09:14 AM EST
Link Posted: 1/1/2007 10:44:55 AM EST
There is no real break in of a new AR to get it to run. If it is lubed properly and nothing is wrong with the assembly or parts it should run.
Link Posted: 1/1/2007 11:27:44 AM EST

Originally Posted By HeavyMetal:
You are describing short recoil.


What are some things that could cause short recoil? The only thing I could narrow it down to was ammo, so is the ammo causing it? Any help is greatly appreciated!
Link Posted: 1/1/2007 12:13:44 PM EST
[Last Edit: 1/1/2007 12:15:47 PM EST by HeavyMetal]
Link Posted: 1/1/2007 12:59:45 PM EST
Check to make sure the gas carrier key is bolted down tightly. Sometimes they loosen and that allows gas to escape which in turn wont cycle the B/C causing a FTF

Also check the gas tube for blockages. If you squirt WD40 into the gas tube from inside the upper receiver, it should drain into the barrel below the FSB.

Link Posted: 1/1/2007 1:23:27 PM EST

Originally Posted By HighStrung1:
Check to make sure the gas carrier key is bolted down tightly. Sometimes they loosen and that allows gas to escape which in turn wont cycle the B/C causing a FTF

Also check the gas tube for blockages. If you squirt WD40 into the gas tube from inside the upper receiver, it should drain into the barrel below the FSB.



Well, I also tried interchanging the BCG from my Bushy into the Sabre Defence. In my Bushy, it work fine. In the Sabre Defence, it doesn't work. I'll try checking the gas tube for blockages, though. But if the gas tube was blocked, wouldn't it FTF no matter what kind of ammo is used?
Link Posted: 1/1/2007 1:38:36 PM EST
Noob Tag
Link Posted: 1/1/2007 1:44:47 PM EST
[Last Edit: 1/1/2007 1:45:26 PM EST by streetfighter]
Link Posted: 1/1/2007 4:56:47 PM EST
I shot some CLP down the gas tube, and it does drain out of the barrel. How would I check for gas leakage from the FSB? What exactly am I looking for? Sorry for the noob questions. I took off the handguards and snapped some photos of the FSB area if that helps any.



Link Posted: 1/1/2007 5:26:47 PM EST
Sorry man, that really sucks. I have the same exact upper from PK and it runs like a top, no FTFs thus far. If you can't find the cause soon I would contact PK, they have excellent customer service.
Link Posted: 1/1/2007 5:33:16 PM EST
[Last Edit: 1/1/2007 5:34:47 PM EST by G-CODE]

Originally Posted By MrLogan13:
Hello everyone, happy new year. Well, in part of my celebrations on New Year's Eve, I went down to the range to do some blasting. I was testing out my new Sabre Defence barreled upper from PK Firearms. But much to my dismay, I discovered some interesting problems.

I started firing with Winchester Q3131 ammo. Fired off one shot. Fired flawlessly, the case was extracted. When I attempted to fire the second round, CLICK. I looked through the ejection port and noticed the bolt didn't lock all the way forward. It was closed, but not locked. It also didn't feed the next round. So I charged it, and fired off the second round. Same thing; bolt didn't lock completely forward and FTF.

I thought it was my magazine maybe, so I switched magazines. Same problem. Tried those magazines in my Bushy M4gery, and they worked flawlessly. Then I tried Lake City M855 ammo. That cycled the weapon properly, and I had no isses with the M855 ammo in the 20" Sabre Defence barreled upper. I thought that was very strange.

Anyone have any idea what might be causing this problem? Is the Q3131 underpowered and causing my rifle to not cycle properly?


I have a Sabre 20" government upper that does a similar thing. It will shoot and eject but fail to pick up a new round unless lubed very wet or if you use only XM193. SA, Guat, and hunting loads completely cycle about 60% of the time. Mine probably needs more rounds thru it as it has only about 150 through it at this time.

I suspect that the new CMT BCG that's in mine is part of the problem as all CMT BCG's I have ever owned have been stiffer than a board. Hopefully it works out that it's just a break in problem as I've checked the carrier key, gas port size, gas tube, and pretty much everything else that may cause such an issue. It kinda sucks as I'm in the opinion that an upper built with quality? components should work with decent ammo right out of the box and not need a couple hundred round break in. We'll see.......
Link Posted: 1/1/2007 6:08:06 PM EST

Originally Posted By G-CODE:

Originally Posted By MrLogan13:
Hello everyone, happy new year. Well, in part of my celebrations on New Year's Eve, I went down to the range to do some blasting. I was testing out my new Sabre Defence barreled upper from PK Firearms. But much to my dismay, I discovered some interesting problems.

I started firing with Winchester Q3131 ammo. Fired off one shot. Fired flawlessly, the case was extracted. When I attempted to fire the second round, CLICK. I looked through the ejection port and noticed the bolt didn't lock all the way forward. It was closed, but not locked. It also didn't feed the next round. So I charged it, and fired off the second round. Same thing; bolt didn't lock completely forward and FTF.

I thought it was my magazine maybe, so I switched magazines. Same problem. Tried those magazines in my Bushy M4gery, and they worked flawlessly. Then I tried Lake City M855 ammo. That cycled the weapon properly, and I had no isses with the M855 ammo in the 20" Sabre Defence barreled upper. I thought that was very strange.

Anyone have any idea what might be causing this problem? Is the Q3131 underpowered and causing my rifle to not cycle properly?


I have a Sabre 20" government upper that does a similar thing. It will shoot and eject but fail to pick up a new round unless lubed very wet or if you use only XM193. SA, Guat, and hunting loads completely cycle about 60% of the time. Mine probably needs more rounds thru it as it has only about 150 through it at this time.

I suspect that the new CMT BCG that's in mine is part of the problem as all CMT BCG's I have ever owned have been stiffer than a board. Hopefully it works out that it's just a break in problem as I've checked the carrier key, gas port size, gas tube, and pretty much everything else that may cause such an issue. It kinda sucks as I'm in the opinion that an upper built with quality? components should work with decent ammo right out of the box and not need a couple hundred round break in. We'll see.......


Yeah, that sucks, man. Hopefully I can "break it in" next weekend. Otherwise, I think I will contact PK.
Link Posted: 1/2/2007 7:45:11 AM EST
First of all, If you are using any extra power recoil springs, or heavier than standard buffers, get rid of them ASAP.

You want a standard weight spring and a standard buffer.

Second, check your gas key, make sure it is tight and the screws are torqued and staked.

Lube the bolt and carrier up properly.

Make sure the bolt group is not binding on the hammer or buffer tube as it moves rearward.

If all this stuff is good, and it still wont run, your gas port is too small. Simple fix.

Link Posted: 1/2/2007 7:49:48 AM EST
Link Posted: 1/2/2007 10:38:55 AM EST
[Last Edit: 1/2/2007 10:39:20 AM EST by SpacemanSpiff]

Originally Posted By HeavyMetal:

Originally Posted By SpacemanSpiff:
First of all, If you are using any extra power recoil springs, or heavier than standard buffers, get rid of them ASAP.

You want a standard weight spring and a standard buffer.

Second, check your gas key, make sure it is tight and the screws are torqued and staked.

Lube the bolt and carrier up properly.

Make sure the bolt group is not binding on the hammer or buffer tube as it moves rearward.

If all this stuff is good, and it still wont run, your gas port is too small. Simple fix.



Very simple fix, it is a waranty item. Send it back to Saber and let them fix it. Drill the gas port and void the warranty.




Why would he send back a perfectly good barrel before he checks this stuff? If everything checks out and he doesnt want to drill the gas port, then send it back.

For me, either way I would fix it myself. I hate shipping stuff out and waiting for it to come back.

enlarging the gas port takes like 10 minutes. The only way to screw it up is to go too big. Just go up one letter size bit and test fire till the bolt locks back on an empty mag.


Link Posted: 1/2/2007 10:50:37 AM EST
[Last Edit: 1/2/2007 10:51:57 AM EST by HeavyMetal]
Link Posted: 1/2/2007 11:10:51 AM EST

Originally Posted By HeavyMetal:
Yes, lets remove the FSB, up one size replace and test and remove and drill and replace and test........thats simply absurd and the cost in time and ammo alone to test and retest make it cheaper to just send it back. That is simply throwing good money after bad.


Let the factory do it. If they fuck it up, they have to replace it. If it turns out not to be the gas port, you just trased your warranty.

Experimentation is only justified if it is an out of warranty item.


Yeah, I don't want to void the warranty. I mean, if they'll fix it or replace it, why mess with it? I just cleaned and lubed the hell out of it, going back to the range on Saturday to see if there's any change.
Link Posted: 1/2/2007 11:38:13 AM EST
Link Posted: 1/2/2007 11:56:11 AM EST
Gas ring alignment. Always a good thing to check out but probably not an issue seeing that you have ammo that works. With the PSI and heat within a gas tube it isn't clogged. I would clean it very well, check the rings and make sure they aren't lined up just for grins and lube the BCG with Mobil 1. Shoot a few hundred rounds if not more with ammo that works, clean and try the ammo that was giving you problems.
Link Posted: 1/2/2007 12:05:54 PM EST
Link Posted: 1/2/2007 12:10:51 PM EST
Link Posted: 1/2/2007 5:07:04 PM EST
don't spray lubricant down your gas tube. You just caused problems by doing so. the high temps/ lubricants cause carbon build up and will plug the gas tube eventually.

advntrjnky
Link Posted: 1/3/2007 3:11:49 AM EST
Link Posted: 1/3/2007 7:27:23 AM EST
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