Warning if you want an Armalite AR10T.


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355sigfan
May 18, 2003, 06:23 AM
Be prepared to buy a good aftermarket trigger for it. Well I took my AR10T out again today. I was shooting with a friend. Anyway we were having fun when something funny happened. I was holding the trigger back during recoil so the gun would not double. It doubled on me twice and three times for my friend. Anyway when I let off the trigger nothing happened. The trigger did not reset. The hammer did not cock. I checked the chamber and fresh round had been chambered. Everything in the feeding and extraction cycle happened, as it should except the hammer did not stay cocked. It must have slipped the sear and followed the bolt carrier forward. I am starting to think the bump firing problems I have had may actually be a trigger, hammer sear engagement problem. Anyway the new trigger should be here soon. I was wondering if I would have to replace the hammer as well. Other than this flaw the gun was a hoot to shoot and the groups were fairly good.

The first shot from a cold bore was 2 inches low like my last time out. This is a good thing. Because if it is consistent I can correct for it. I will just have to remember to aim 2 inches high for the first round. Although these problems are starting to make me see why Bolt actions are the preferred 308-sniper platform.

PAT

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AK103K
May 18, 2003, 08:18 AM
I'd be willing to bet, that if you have been "bumping" your rifle, that this is the cause of the problem. I would also bet that Armalite would consider it abuse. Personally, I think it is and I also think its an unsafe act, but thats just me. I dont understand why you need to "think about" holding the trigger to the rear. Seems that would be very distracting. You should just pull the trigger and not worry about anything but your sights, it will take care of itself. If not, something is wrong. Did this problem occur before you started "bumping" it or after?
I dont understand the cold bore/2" low thing either. That sounds more like something your doing rather than the rifle. Maybe its your trying to hold the trigger back when you shoot. Your first shot isnt trying to compensate for it like the ones that follow.
Keep in mind, if your close to the target and holding right on it, you will be about 2" low as thats the difference between the sights and the bore.

TechBrute
May 18, 2003, 12:26 PM
:confused:

http://www.ar15.com/forums/topic.html?b=3&f=62&t=160322

Nero Steptoe
May 18, 2003, 02:36 PM
Couldn't help but notice that this exact thread has been pretty satisfactorily covered on GT, in the "Highpower" forum.

355sigfan
May 18, 2003, 03:03 PM
I'd be willing to bet, that if you have been "bumping" your rifle, that this is the cause of the problem
END

Read my post I covered the bump firing posibility. That might explain the doubles but not the hammer not remaining cocked. The first shot flyier was also a problem in a recent article where an AR10 was evaluated. This combined with the fact that I don't somehow make my Rem 700 have a first shot flyer. Also if I am the cause of the problem why does the problem not surface when I fire my chiefs SR25. Heck why has the problem not showed its face with my M1A that I used to own or the FAL's I have shot. This is not the first semi auto 308 I have shot. Anyway I have a new trigger on the way we will see if that cures the problem.
PAT

Kharn
May 18, 2003, 03:59 PM
I was holding the trigger back during recoil so the gun would not double.

The hammer was dropping when you released the trigger in addition to when you pulled it?
Your disconnector isnt grabbing the hammer correctly. Either the trigger and hammer pins are slightly out of place (0.002" farther apart from spec position will do it, IIRC), or your trigger group needs a little tuning. I doubt your lower was made wrong, but you might want to check it with a milling machine and centerfinder. Try filing a very little bit off the bottom surface of the disconnector tail and see if that improves things.

And you bump fired an AR10T?! :what:

Kharn

355sigfan
May 18, 2003, 04:19 PM
Thanks Kharn but it was not firing on release as you described. Which as you said would be a disconecter issue. But rather the hammer was following the bolt carrier forward and not staying cocked. Probably a hammer trigger sear engagement issue.
PAT

Kharn
May 18, 2003, 04:20 PM
How old is this rifle? How many rounds have you shot through it?
Do you have an AR15 you could borrow a trigger group from?

Kharn

goon
May 18, 2003, 05:02 PM
On the topic of bumping, can't the gun fire out of battery when you do that?
I mean, since there is no auto-sear to "wait" until the gun is locked up, couldn't it fire while the bolt is still closing?

Andrew Wyatt
May 18, 2003, 05:26 PM
yeesh. he said bump firing might have been the cause of the doubles, not that he did it on purpose.

AK103K
May 18, 2003, 05:29 PM
yeesh. he said bump firing might have been the cause of the doubles, not that he did it on purpose.
What the hell does that mean? Are you a politician
or a CNN poll question writer? :)

Andrew Wyatt
May 18, 2003, 07:14 PM
it's possible to bump fire an m-1A without actively causing it to happen by not holding it tight enough. it's possible the same thing happened with his ar 10.

AK103K
May 18, 2003, 07:39 PM
OK, I understand what your saying now. The way his post read I took it to mean the other, intentional bump firing.

355sigfan
May 18, 2003, 09:10 PM
On the topic of bumping, can't the gun fire out of battery when you do that?
I mean, since there is no auto-sear to "wait" until the gun is locked up, couldn't it fire while the bolt is still closing?

END

I was not bump firing on purpose. Also the AR15 series will not fire out of battery. If the bolt is open at all the firing pin will not reach the chamber.
PAT

355sigfan
May 18, 2003, 09:11 PM
The rifle is brand new with less than 200 rounds on it. And I have a new trigger on the way.
PAT

Badger Arms
May 18, 2003, 09:35 PM
Pat:

As you described the problem, you might have a disconnector that is not properly engaging the hammer. A good cleaning of the trigger 'groove' in which the disconnector rides would probably clear up the problem. If there is a burr or other obstruction in that groove, the secondary sear (or disconnector) will fail to reliably hold the hammer back. Without a more thorough examination of the gun, that's about all I can tell you. Do you know how to disassemble the trigger group without damaging the gun?

By doubling, do you mean that you 1) pull the trigger and hold it back and then get two shots; 2) you pull the trigger back and get one shot and then release it and get another; 3) or a mix of these two things? You can 'reliably' get the gun to duplicate condition (2) when you by placing an obstruction under the front of the disconnector or filing the engagement surfaces. This releases the hammer when you release the trigger. Two shots per pull and release of the trigger reliably. Condidion (1) and (3) are more likely a burr, minimal sear engagement, or other obstruction preventing safe engagement. A good cleaning and inspection will almost always solve these problems. From the factory, Armalite parts have a very healthy amount of sear engagement. Unfortunately, I have never examined one of their match trigger assemblies which are included with the gun. Is it adjustable? If so, just back off of the adjustments some.

http://www.armalite.com/shared/images/NMtwostagetrigger.gif

355sigfan
May 18, 2003, 09:40 PM
Badger thanks for the post. I just compleated an armorers school for AR15's myself. Its not firing on release. What happens is it doubles when I release the trigger prior to the recoil breaking on the shot. When I hold the trigger and ride the recoil the hammer simply follows the bold carrier forward and does not fire the round in the chamber. I have a new trigger on the way complete with a new disconecter. I will see if that cures the problem if it does not I will buy a new hammer. I am through trying to work with Armalite on the issue they were not much help. Their warranty is not worth the paper its written on.
PAT

Badger Arms
May 18, 2003, 09:44 PM
Is it the trigger in the picture above? Is it adjustable? Perhaps it came from the factory with too-little engagement and this can be corrected by adjustment? I'm sure a new trigger will solve the problem, but others might have the same problem.

Kharn
May 18, 2003, 09:46 PM
What happens is it doubles when I release the trigger prior to the recoil breaking on the shot. When I hold the trigger and ride the recoil the hammer simply follows the bold carrier forward and does not fire the round in the chamber.

So if you tap the trigger and remove your finger as quickly as possible, it fires, but if you hold the trigger down, the hammer drops but does not ignite the round?

Kharn

355sigfan
May 18, 2003, 09:47 PM
To be honest I was going to wait until the Knight trigger came in to take the trigger and hammer out.
PAT

355sigfan
May 18, 2003, 09:50 PM
I am sorry for not being clear. This is what happens. It normally fires when the trigger is pulled. What sometimes happens is that the gun fires twice when the trigger is pulled if constant pressure is not held on the trigger while the gun recoils. Sometimes when the trigger is held to the rear following a shot I go to let the trigger reset and fire another round and the trigger does not reset. I take the mag out and check the chamber and their is always a loaded round in the chamber. The amount of effort to check the chamber tells me the hammer is not cocked.
PAT

Kharn
May 18, 2003, 10:05 PM
I'd try cleaning the trigger and disconnector channel, trying a different disconnector spring and then try filing a little bit off the disconnector tail. Taking apart the trigger group is easy to do, and just dropping in another trigger will only cover up your problem instead of getting to the bottom of it.

Kharn

355sigfan
May 18, 2003, 10:08 PM
Kharn. Thanks I understand its easy. Like I said I just compleated a Colt Ar15 Armorers course. But the reason I am hesitant to make this trigger work is it has been back to Armalite 2 times. I am simply tired of dealing with it. Besides I like the pull better on the KAC trigger. I tried in on my chiefs SR25.
PAT

Art Eatman
May 18, 2003, 10:28 PM
AK103K, re your comment, "I dont understand the cold bore/2" low thing either."

I've occasionally had a bolt-action rifle where the first shot from a cold AND clean barrel would be an inch or two off from the next five or ten shots. No idea why.

One of my father's sporterized Springfields always shot 2" high, the first shot from a cold barrel. The next umpteen rounds would hold a tight group and impact where intended, 2" high at 100 yards. He rebedded the rifle, and then later changed the barrel--and no change in behavior. Go figure.

:), Art

AK103K
May 19, 2003, 07:27 AM
Also the AR15 series will not fire out of battery. If the bolt is open at all the firing pin will not reach the chamber.
This isnt the only reason it can slam. The M1 Garand has a firing pin block that is supposed to block the firing pin until its in battery, but that still doesnt guarantee it wont slam, I can personally attest to that. All it takes is a high or sensitive primer and some knucklehead doing the "bump". Actually, it wouldnt even take that to make it slam. Never say never with anything mechanical.

mummac
May 19, 2003, 08:14 AM
What is bump firing? I'm asking just to know not to try. It doesn't sound too healthy.

Kharn
May 19, 2003, 08:55 AM
Mummac:
Bump firing is when you hold a semiauto rifle loosely, pulling it forward with your left hand, while your trigger hand does not grip the gun but only pulls the trigger. The recoil of the firearm pushes the gun away from your trigger finger, reseting the trigger, and your support hand pulls the trigger back to your finger, thus simulating full-auto fire. Its not very good for the gun, especially match-grade rifles.

Kharn

355sigfan
May 19, 2003, 12:38 PM
IT can't slam fire unless the bolt closes and is in battery. If the bolt is open and unlocked the firing pin is not long enough to contact the primer. ITs a build in safety feature that I did not know about myself until completing an armorers course.
PAT

Kharn
May 19, 2003, 02:22 PM
355Sig:
Another thought, look at the underside of your AR10's bolt carrier and the front face of your hammer. Is the firing pin exposed like in a normal AR15 bolt carrier, or shrouded like an M16's? Click here for a picture (http://www.ar15.com/content/docs/AR15-M16Parts/boltCarrier2.gif) Also, does your hammer have the notch on the front intended to catch the carrier, or is it rounded like an M16's? (I'm not talking about the autosear hook)Click here for picture (http://www.ar15.com/content/docs/AR15-M16Parts/hammer.gif)

It is intriguing that your bolt carrier isnt being caught by the hammer before closing, that is supposed to be a safety mechanism to prevent exactly what is happening (hammer falling without being delayed by autosear, thus in a semiauto, no doubling or full auto possible with that style of hammer).

Kharn

AK103K
May 19, 2003, 03:54 PM
IT can't slam fire unless the bolt closes and is in battery. If the bolt is open and unlocked the firing pin is not long enough to contact the primer. ITs a build in safety feature that I did not know about myself until completing an armorers course.
355sigfan,
It CAN slam and the fing pin doesnt have to contact the primer. The bolt itself can cause the slam in the right circumstances, especially with high primers in reloads. There is also the possibility that the firing pin breaks and is stuck forward like an open bolt gun and will also cause the gun to fire. A lot of things that are not supposed to happen can and do.
The M1's and M14s have a cross member in the reciever with a slot in it and hooked firing pin which rides on the cross member until the bolt goes to battery allowing the pin to clear the slot and then reach the primer. This is ITS firing pin safety. Its not "supposed" to slam either, but mine sure as hell did. There was no primer in the pocket in the lower remaining half of the case. I'll never know if the pin hit it or not. The round was obviously not fully in the chamber when it went off. This was also with Lake City factory ammo, not reloads. Just because its not supposed to doesnt mean it cant or wont. After seeing what a slam fire can do to a steel rifle like the M1, I sure wouldnt want to see what happened to an AR that had one.

BusMaster007
May 19, 2003, 04:36 PM
...not exactly relevant, but...
If this isn't too far off of the thread subject, can someone describe the differences between open and closed bolt guns?

The term 'open bolt' was used above, with the statement of 'firing pin stuck forward'...
I always wondered what the difference was between open and closed bolt in a machine gun.

Does this mean that the open bolt design has the firing pin 'sticking out there' on purpose, so as to continue the cycle until the ammo is gone, or?

AK103K
May 19, 2003, 05:54 PM
Open bolt guns fire just as its described. The bolt is open and released when the trigger is pulled. It moves forward and strips a round from the mag as it goes and fires when the round goes home. Most have a fixed firing pin. A closed bolt gun is just what most of your semi auto rifles are. The M16, AK, Mp5, ect, are closed bolt and full auto guns. The bolt goes home and locks up before it fires.

355sigfan
May 19, 2003, 06:03 PM
There are only two ways for a round to fire in a AR15 M16. One is if the firing pin hits the primer with sufficient force t detonate it. This can occure when the hammer strikes the with the bolt in the locked position. Or it can occur if you have sensitve primers from inertia of the firing pin slamming forward when the bolt carrier comes to rest at the end of its cycle. The only other way for the gun to fire is a cook off form heat detonation. The gun can not slam fire with the bolt in any postiion but locked. What can cause a AR15 M16 to blow up is if you don't put the cam pin back into the bolt assembly. Then if you manage to get unlucky enough for the lugs to line up and allow the rifle to fire you get a blow back ar15 which in reality is a bomb.

The firing pin is not long enough to touch the primer until the bolt is locked into place. There is no way for the bolt to fire the weapon with out the firing pin contacting the primer. Now the AK47 is a different animal from my understanding and it can fire when its not locked up. But I don't know that first hand because I am not a AK 47 armorer I am a Colt M16 AR15 armorer. I suppose with extreemly high primers the gun could possibly fire with out the help of the firing pin but I have never heard of that happening. Also why would you shoot ammo with high primers.

PAT

AK103K
May 19, 2003, 06:44 PM
The gun can not slam fire with the bolt in any postiion but locked.
I was always taught this too, they said the same thing about the M1/M14, I've found out otherwise and lived to tell you about it. If the rifle was in my shoulder, I wouldnt be, as the rear of the reciever would have gone through my eye. These things are man made tools. They are not perfect. Things that are not supposed to happen, do. The M1/M14 series rifles are supposed to have a fail safe too. My rifle was obviously out of battery when it went. I'm not foolish enough to believe that an AR/M16 cant do it too, or any other rifle for that matter. There are to many "possible" things that can go wrong, especially when reloaded ammo comes into the mix.

Also why would you shoot ammo with high primers.
Have you ever shot reloads out of your rifle? Have you shot someone elses in your gun or theirs? Do you mike the primers? If you dont, how do you know they are right? You would be amazed at the numer of what I would have called good, fail when you mike them. This was one of the "possible" causes of a slam fire that wasnt "supposed" to be able to happen. It was with issue, Lake City 69 30/06, not reloads. Did the arsenal screw up? Who knows. I'm real picky about ammo I shoot in these type rifles. Actually, I'm real picky period.

Things CAN happen, no matter how many times your told they cant.

260Rem
May 21, 2003, 10:17 AM
Reading all of this and thinking carefully, I seem to recall that my little brother managed to make an AR-15 fire out of battery. Case buldged, primer blew, all kinds of havoc to the brass basically. The gun kept going without a burp. As a matter of fact, it is STILL ticking along just fine. But when we picked up the case my brother had fired, it was obvious that it had gone off out-of-battery. How else could 1/2" of the case have swollen to almost the diameter of a .30-06 base? Plus, like I said, the primer was gone and the brass was toast. Yet the rifle held together and my brother didn't even realize anything bad had happened!

So anything is possible gentlemen, and it is good to remember that! And I won't even start about my .260 that will give 1/2", 100 yard groups ONLY if the brass has been once or twice fired...

Black Dragon
May 21, 2003, 11:23 AM
My father-in-law sent me a picture of a AR-15 that had the round fire BEFORE the bolt was locked! As everyone says, you have a small bomb in your hands. The rifle was blown apart. I believe this was from the AR15.com web site. I have a picture on my computer but I have no idea how to post it here. Sorry.

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