AR10 malfunction

[stagpanther]

Stagpanther...they weren't subcontracted to Sudan..they were built in the Netherlands and sold to Sudan.
The selector says Safe , Semi Auto , Auto.
And no...he's keeping it

Slamfire...My friend is actually fastidious with his firearm maintenance

Will let you know what we find. He should be bringing it over in the next day or two.

If you can--please take pictures and post--it's rare we yanks get to see a piece of history like that. Sounds like the weapon most likely is full-auto capable--or was--given the selector settings. I would definitely be concerned about whether or not you're getting proper BCG to extension line up/lock up and proper headspacing, it's not all that hard to check. If nothing else--I'm sure somebody would be willing to pay a handsome price for it if your friend decides he doesn't really need it. As far as I know--there was only a few to 5 thousand honest-to-God AR-10's made before the whole "great 5.56 hijack" took place--forever altering American military history.

[ronl]

I thought having such a rifle in your part of the world was highly restricted. Sounds to me as though you may indeed have a full auto rifle. Is there a pin just above the selector lever?

[doc raven]

OK. he was just here. We completely stripped and cleaned it. It was very clean inside apart from a little carbon on the back of the bolt. Cleaned that off and inspected everything thoroughly. No damage. Nothing looked like it had been played with from factory. No marks or wear on sear surfaces nor any damage.

There is not a spring on the firing pin like ya showed me in the photos.
The Rifle looked nearly pristine inside. Id be surprised if the rifle had ever had more than a couple hundred rounds through it in its life. Head space was fine. Bore is excellent. FCG looked like new. Even inspected with an eye loupe. Everything operated perfectly.
I am starting to believe that it was the Federal ammo. Next step will be to head to the range and will test with different ammo and if it doesnt fault, Then will retest with the federal ammo carefully.
There was nothing obvious in or on the buffer or tube. all clean with very little wear marks. no burrs. spring in good condition. Same with the buffer itself.

Sorry I didn't get any photos. Only saw ya post after he'd left. Will try to remember when we go to the range.

[doc raven]

another thing no one has mentioned yet which I originally asked in my first post was about the ejecting angle. All the videos I've watched of these AR-10's being fired shows in 90 % of cases the ejected brass is exiting between 1 and 3 o clock. I read on a post somewhere that this has to do with the gas system but nowhere so far have I found anything that goes into more detail. I did notice on the day we were at the range that all of his brass was ejecting to 5 o clock instead of the 1-3 o clock angle. Does this matter or is it also an indicator of a problem?

[stagpanther]

another thing no one has mentioned yet which I originally asked in my first post was about the ejecting angle. All the videos I've watched of these AR-10's being fired shows in 90 % of cases the ejected brass is exiting between 1 and 3 o clock. I read on a post somewhere that this has to do with the gas system but nowhere so far have I found anything that goes into more detail. I did notice on the day we were at the range that all of his brass was ejecting to 5 o clock instead of the 1-3 o clock angle. Does this matter or is it also an indicator of a problem?

The "ejection angle clock" is a rough approximation of the relative gas pressure within the reciever/carrier--the theory being that exiting forward of the 3:00 you're likely over-pressured, somewhere in the 3:00 to 4:30/5:00 you're good and aft of that you're under-gassed.

My experience is that this can vary depending on the gas system set-up and power of ammo used--especially in the xx308 builds I've done. Even the type of powder and when it reaches peak pressure can cause variations in the whole cycling process. Adjustable gas block manufacturers will tell you that the mechanical symptoms of an over-pressured system may resemble exactly those of an under-pressured one (short-stroking, failure to eject etc.). I have verified that to be true in my experience.

You mention everything looks pristine and virtually unused--but that does not necessarily mean it is fully compliant. It only takes a few thousandths of an inch variation to potentially create a dangerous condition. People assume sitting in a safe unused means that weapons remain in tune--could be--but the opposite could also be true.

[hodaka]

5 o'clock is good. Different ammo will throw brass differently. Has to do with gas flow and speed of bolt movement. Sounds like the lack of hammer spring and sensitive Federal primers caused the issue.

[Mobuck]

If you're REALLY concerned about the multiple firing problem, go through the complete "new gun start up procedure". This will tell you if there's a problem with the FCG.
Oh, don't spare the lube during range sessions. If the rifle smokes like it's on fire, it's lubed adequately.

[doc raven]

Ok. That answers that. Thanks guys

[ed308]

The first AR I assembled back in the early 90's had a similar problem. It would frequently fire 2-3 rounds. I couldn't figure out was wrong with it but happened to be at a range when a machinist familiar with AR's looked at. He determined the opening on the gas key was out of round. Replaced the part and no problems since with thousands of round fired through that AR.

[navajo]

What does the roll mark say? Should be on the mag well

[doc raven]

OK. We went to the range this afternoon. The rifle performed flawlessly! After tentatively firing 10 mags loaded with two rounds each, He fired 6 20 round mags full of Winchester ammo without any problems. He then loaded 2 rounds of Federal ammo and it burst the two rounds. Luckily that was the last of his Federal .308 ammo so the problem won't be happening again. I then fired 40 rounds of the Winchester ammo without a fault. He now knows to keep it wet too.
Thanks to everyone for all the help.
Once again you all have been a great source of information and help.
Cheers

[Slamfire]

After tentatively firing 10 mags loaded with two rounds each, He fired 6 20 round mags full of Winchester ammo without any problems. He then loaded 2 rounds of Federal ammo and it burst the two rounds. Luckily that was the last of his Federal .308 ammo so the problem won't be happening again. I then fired 40 rounds of the Winchester ammo without a fault.

Good to know.

I don't know if you or your bud reload, but if reloads are to be used in this rifle, use "mil spec" primers. In the United States, the least sensitive primer is the CCI #34. The US Army developed a non corrosive large rifle primer and it was called the #34 primer. There are lots of primers, each of a different size, each of a different composition, and each of a different sensitivity. The #34 primer is a little less sensitive, on the average, than the commercial primers. That includes CCI standard, Winchester, and of course Federal.

Before the US got into a trade war with Russia, Tula primers were available, were advertised as "mil spec" and they were a great primer.

I am going to reference this thread in the future as it is a good object lesson. It is hard to believe but for over a half century the American shooting community were taught that "only high primers" and your worn out receiver bridge were the allowable causes of slamfires. It turns it this was a 60 plus year cover up of the design faults of the Garand type mechanism. The Garand, like the AR10, has a free floating firing pin. Unlike the AR mechanism, the free floating firing pin in the Garand mechanism is able to contact the primer before the lugs are in battery. Many shooters were injured, many Garands/M1a were blown up when their rifles slamfired out of battery. Both the Army, and their sock puppets on the American Rifleman staff, created a disinformation campaign claiming there was nothing wrong with the Garand/M14, that slamfires were all the fault of reloaders and their high primers. I can remember in the mid 1990's arguing this on the "Shooter's Forum". At the time, primer sensitivity was not a concept, the shooting community had been taught by these same sock puppets that a primer was a primer was a primer. Federal match primers were the most popular primer on the firing line, because, Federal was the only company stamping "match" on their box of primers, and of course, if you are a match shooter, you want to use match components. It turns out Federal primers are the most sensitive primer on the market by design, so reloaders were using the absolute most dangerous primers in their Garands./M1a's. And none of the in print media warned the shooting community about this.

The in print media still basically ignores this, that primers do vary by sensitivity and that in semi auto's, full auto's, you should use the least sensitive primers you can find. This is glossed over because the in print media is not going to print anything prejudicial to their advertisers. They are there to educate us on what to buy, not to teach us what not to buy. If you model in print media as shills for the fire arm industry, then their behaviors become understandable as rational, predictable, and amoral.

Since the 1990's, the internet community is able to discuss intelligently these issues, free of commercial profit motives, and I am pleased to read very good analyses of slamfires such as what I found here:

Slamfire

https://ipfs.io/ipfs/QmXoypizjW3WknF.../Slamfire.html

Something that is to be understood, even with "mil spec" primers, all mechanisms with free floating firing pins can, and have, and will, slamfire because primer sensitive varies so much within a lot. Primers have to meet an average lot sensitivity, but if you ever get to see actual primer sensitivity data, you will see primers within the lot that take very little energy to ignite, be they commercial or mil spec. Therefore, when loading a military type rifle, don't point the muzzle at anything you don't want to kill. The things may slamfire.

This is a tavor TAR 21, which fired well with factory federal, but slamfired upon reloading with winchester ammunition.

https://www.youtube.com/watch?v=bu8Dwj7Ey8k

Winchester primers vary in sensitivity, they vary by lot, so the next batch of Winchester ammunition, it may also slamfire. Commercial manufacturers are free to change their product as they want.

[doc raven]

I must admit I should have twigged to the Federal thing sooner. When I was shooting Cowboy action I competed in Frontier Cartridge class which was using cartridges loaded with black powder. For other competition such as IPSC , Service pistol etc I had always used Federal primers in my ammo ( yes we both reload too) but when I started shooting Cowboy the black powder was too hot and I was blowing holes in my primers. I changed to CCI and haven't looked back.

[stagpanther]

With all due respect to you and slamfire--I'm not buying the federal primer thing as your sole and only problem. Are you using commercial grade 308 win instead of actual nato 7.62 x 51 (which is what the rifle was designed to eat)? There's no doubt that the primers are different (as are the cases and the primer seating)--but the Nato ammo was never designed to function or be used interchangeably with it's 308 civie counterpart. You mentioned a faulty bolt to extension lock-up--if you are absolutely certain that is attributable to the ammo--then fine, but just getting a few mags to successfully cycle through may or may not indicate there is or is not an issue there. Just sayin'-- not trying to be snarky, just trying to say "are you sure?"

[T. O'Heir]

"...needs to use a LOT of lube..." The thing needs a really good bath first. Dried lube isn't going to cause doubling though
A semi going FA is caused by the ammo or a worn sear/hammer. Mind you, an M-14 will double off a bench if the shooter doesn't follow through correctly. Caused by failing to hold the trigger back until the rifle finishes recoiling and pulling the trigger again under recoil. That may be the cause here too.
The military issues whatever ammo the politicals buy for them. The only relation it has to being "appropriate for your rifle" is that it's the same cartridge. Original AR-10's were made to use standard NATO ball.
Slam fires are caused by the ammo, not the rifle
"...simply call Armalite customer service..." Neither the current commercial AR-10's(that's an AR-10 in name only) nor the current company called Armalite have anything to do with a real, select fire, 1950's vintage AR-10. And Gladstone, Queensland is in Australia.
The Sudanese AR-10's(rumoured to be approximately 2500 rifles) that came through the shop, long ago, still had parts of the desert in 'em. Full of sand. Really poor maintenance by Abdul dragging 'em around the Nubian Desert. I don't recall there being any Sudanese 'government' markings.
Supposedly, they had a very lightweight, fluted steel barrel fitted with a trim, prong-style flash suppressor, a bayonet lug, lightweight fiberglass furniture, and sight graduations in Arabic.

[Slamfire]

All you have to do is search the web for slamfire incidents and it becomes obvious that these happen, that sensitive primers are the primary cause, and, it is the simplest explanation for these events:


SLAMFIRE IN SKS


7 Dec 2010

Ammunition companies are very reluctant to admit any type of error that may make them liable. I bought a Norinco SKS in 92, after shooting several boxes of the cheap import ammo I bought a couple of "good" remington ammo for hunting. I took it to the range, loaded the gun and dropped the bolt, BOOM, a round went flying down range. I thought "damn, I must have brushed the trigger when I dropped the bolt." I aimed the gun down range a squeezed the trigger, boom boom boom, three rounds lit off. I very carefully unloaded the gun and went home and called Remington, a week and three phone calls and they never did admit any fault, they said I hadn't cleaned my gun well enough and some cosmoline stuck around the firing pin was the culprit. It's a good thing I practice gun safety and keep a loaded gun pointed in a safe direction at all times or someone could have been hurt or killed and Remington still would have said it was my fault. Just last year I discovered that shortly after that they changed the components they used to manufacture their 7.62x39 rounds.

http://www.thehighroad.org/showthrea...44#post6193244

AK47 Saiga Slamfire

I have a Russian Saiga 7.62x39 That I love more than anything to shoot. The other day I took it and a few hand guns to the range (in door) The weekend before I picked up 700 rounds of the military ammo at the gun show Boy did I have a rude awakening. Slipped in a 30 round mag, dropped the bolt and un loaded 30 rounds without a miss fire. You have no idea how quiet it got there. I had the range officer on me so fast. After a lot of wounderment we found the problem. The primers in the military loads are soft. I have seen that happen in the SKS but never in an AK. I guess I wanted to share this adventure with everyone and a warning. With the range dude there I loaded up a 5 round with this ammo and it did it again. I then re loaded the 5 round mag with some Wolf 122gr. HP Steel Case and everything went back to normal. Just wanted to share this miss hap and be sure where your muzzle is pointing when you lock and load.

They came loose in a can which my brother has. I will contact him and tell you just what is was. I do think I remember that there were 500 Rounds military Surplus. Egyptian

Sensitive American commercial primers have also caused recalls of several military weapon types, which were then fitted with firing pin springs.

20 Feb 2008 Shotgun News,
Article “ Micro Galil, The Ultimate Krinkov”
Author Peter Kokalis

Page 12

“Most Kalashnikovs have inertia firing pins, without an associated spring. The initial lot of Galils brought into this country by Magnum Research INC. also had no firing pin springs. The Micro Galils that I examined in El Salvador were not equipped with spring-loaded firing pins either.

Military small arms ammunition primers usually have relatively hard cups, which are not easily touched off. American commercial cal .223 Rem ammunition, including Winchester ammunition often features fairly soft primer cups. In 1983, Winchester ammunition in particular caused several slam-fires and all Galils offered for sale in the United States were quickly retrofitted with strong firing pin strings. “

29 August 2007

CENTURY INTERNATIONAL ARMS, INC.
236 Bryce Boulevard
Fairfax, Vermont, U.S.A. 05454
Tel: (802) 527-1252 Fax: (802) 527-5631
Date: August 29, 2007

Subject: Galil and/or Golani Semi-Auto Sporter Rifle

We are requesting that customers who purchased the Galil and/or Golani Semi-Auto Sporter that have serial numbers between GAL00001 and GAL02393 send in their firearm to us as we have modified the bolt and are installing a new firing pin and firing pin spring to ensure that your Golani offers you the utmost safety and reliability. All Galil and/or Golani rifles that have the letter "F" or "X" on the bottom of the receiver front cut off have already been upgraded and your rifle does not need to be sent in to us.If you are a dealer, please provide us with the names, addresses and contact information of the purchasers of these Galil/Golani rifles. We will contact them directly. If you are contacted by these customers, please have them call us at 1-800-270-2767 to obtain a return authorization. We appreciate your cooperation in this matter and hope to have this situation resolved as quickly as possible

[stagpanther]

Slamfires happen sure because of ammo/primers--not saying they don't. My take on the initial description is that there is potentially more than just that going on. What is the protrusion of the pin past the bolt face? Is it sharp/round? Could it be hanging up inside the bolt allowing it to "overimpact" the primer,? is there proper bolt to extension lock-up and headspacing? these are just a few of the things I'd want to know with some degree of certainty.

[doc raven]

The end of the firing pin is round not sharp. The bolt is locking up fine and head space is spot on. The rifle was very clean when purchased and there are hardly any wear marks inside on any of the moving parts.

[stagpanther]

The end of the firing pin is round not sharp. The bolt is locking up fine and head space is spot on. The rifle was very clean when purchased and there are hardly any wear marks inside on any of the moving parts.

Good --and you're sure the fire control group is also in compliance? It seemed to me you were not sure if it was equipped to be semi-auto only or select-fire/auto capable.

[doc raven]

It is all good. working correctly and in excellent condition. Im fully aware if it is equipped to be semi auto only or select fire/auto capable