AR-15 Fail to feed issues

Joined
May 28, 2009
Messages
3,520
Likes
340
Feedback: 19 / 0 / 0
At the Pumpkin shoot my AR was giving me a lot of sh*t to say the least.

I found that the Bolt Carrier Key Screws came loose and no longer line up with the notches from the factory.

Can/Should I use locktite to keep them from coming loose?
 
You should probably use red loctite AND get the carrier key staked. Basically someone has to peen the metal over on the screws so that they will not move under any circumstances. Any AR smith will be able to do this for you easily.

-Mike
 
Ok, I can do that. Should I torque it, or just line it up with the factory stakes and re-stake it?
 
Don't know if the factory would stake your gas keys. As Mike said call around to some of the smiths, they can do it for you. I think Umlat Arms up in NH does it for like $10.

Oh, it's staked. It was a PITA to get the allen wrench into the bolts. I already fixed it, just need to get back to the range to test it. [smile]
 
What is the make/model on the rifle and BCG? Quite a few companies don't stake/improperly stake the keys.

Here is a suggestion by an experienced gunsmith from another board:
Torque spec according to US Mil standards for bolt carrier key screws = 35 INCH pounds to 40 INCH lbs.

I go to 55 INCH lbs on them and use red Loc-Tite occasionally and always stake the key into the heads of the screws. At 55 INCH lbs with quality carrier keys and screws I've not seen any come loose, warp the key nor fail in any way.

Complete thread
 
What is the make/model on the rifle and BCG? Quite a few companies don't stake/improperly stake the keys.

Here is a suggestion by an experienced gunsmith from another board:


Complete thread

Thanks. Its a Stag Model 3. I torqued it to 50 in/lbs, and used a dab of loc-tite, then staked each bolt twice. I haven't had a chance to test yet. Hopefully tomorrow [smile]
 
I'd be on the phone to Stag. Improperly staked keys are bad juju - some of the larger manufacturers, (Bushmaster, DPMS, Stag) don't seem to be keeping up on their QC - especially properly staking a carrier key. I wish I would have known, I have a spare BCM M-16 carrier group in my range bag - it could have been yours for the day...Speaking of which, a spare BCG is cheap insurance to a productive outing. At $130.00, it's not a hard expense to swallow and keep one in your kit...
 
I heard a rumor that the the screws were staked to keep the troops in the field from disassembling the bolt carrier. Staking isn't really necessary.
 
Staking is absolutely necessary. An improperly staked key can freeze up the action so badly that you'd almost rather get a new upper.
 
Staking is absolutely necessary. An improperly staked key can freeze up the action so badly that you'd almost rather get a new upper.

Yuppers. It's a bad scene. Tim, if you do a search on any of the popular AR sites, or even just a Bing Search for "loose carrier key", you'll hear and see some horror stories. You were one bolt drop away from potential disaster. Carrier keys - especially in the violent action of short-tube AR's are a weak-link if they're not properly done. I'd seriously consider having your bolt properly done, or buy a Moaks tool to do it yourself. There are even people who will do it for you for free. In any case, I'd skip the LocTite and have this pup staked...Go to Bravo Company USA and get yourself one done right. Their M-16 Bolt Carrier Groups are $130.00....
 
"Rumor" being the operative word. Staking does not prevent dis assembly of anything. It just makes it harder for screws to loosen. The military TDP specifies staking for a reason. Just like not staking the receiver end plate on carbine receiver extensions.
I heard a rumor that the the screws were staked to keep the troops in the field from disassembling the bolt carrier. Staking isn't really necessary.
 
Success-Kid-YOU-BROKE-YOUR-AR-AK-TI.jpg
 
Staking is absolutely necessary. An improperly staked key can freeze up the action so badly that you'd almost rather get a new upper.

Agreed, staking of the gas key screws is necessary as they take the full impact of the blowback gasses. Even if they are locktited, they can still loosen as heat transfer from hot gasses can reduce the locktites's holding abilities and chronic impact will loosen almost anything over time. A mechanical staking almost guarantees that the screws will never back out.

Worked on and built alot of ARs over the years and I've never seen a factory gas key/BC group that wasn't staked, it must have been missed in QC check......not good.
 
Agreed, staking of the gas key screws is necessary as they take the full impact of the blowback gasses. Even if they are locktited, they can still loosen as heat transfer from hot gasses can reduce the locktites's holding abilities and chronic impact will loosen almost anything over time. A mechanical staking almost guarantees that the screws will never back out.

Worked on and built alot of ARs over the years and I've never seen a factory gas key/BC group that wasn't staked, it must have been missed in QC check......not good.

It's becoming near epidemic with Bushmaster, DPMS and Stag....
 
Is there any magic to this? Can you just use a center punch? What's a Moaks tool?

Jim, it is an expensive tool used to stake the carrier key. I believe there are 2 versions of it now. If you put Moaks tool in your search engine it will come up with places you can buy it etc. I have never used one but it is my understanding that they are not difficult to use.
I bought a different tool from Brownells that is for staking the carrier key but I have not tried it yet.
 
Is there any magic to this? Can you just use a center punch? What's a Moaks tool?

In a word, yes. You can indeed use a punch - I have seen a couple done this way and they looked good. The problem is that actually moving the metal to cover the bolts is not easy - the Moaks makes it easier and more effective.

There's a good discussion on the benefits of not only the Moacks, but staking in general here:

http://m4carbine.net/showthread.php?t=5063


http://m4carbine.net/showthread.php?t=7463

There are some who possess the tool that will send it to you in good faith to use, or stake your carrier key properly for free...
 
Is there anything in particular to look for to see if this is a problem? I have a new Bushmaster that has about 50 rounds through it. I'd like to head off trouble if at all possible.
 
Is there anything in particular to look for to see if this is a problem? I have a new Bushmaster that has about 50 rounds through it. I'd like to head off trouble if at all possible.

Yes, look to see that there is sufficient metal from the staking covering the screw head if staked on top, or sufficient dent to grip the knurling on the side of the screw head if staked from the sides.

Personally, I like a top stake as it puts metel on top of the screw so it can't back out.
 
Already thought about that, a couple more weeks. [smile]

Is there any magic to this? Can you just use a center punch? What's a Moaks tool?
I used a punch, gonna test it out hopefully today. If it comes loose again I'll send it to stag.
I thought Nicole broke it? [smile][wink]
[laugh2] As much as I'd love to blame someone else, this ones on me for not double checking my rifle. [wink]

Thanks for all your help guys.
 
I also had problems with FTF on my Stag AR...I'll go and check the BCG, but could the problem lie elsewhere? Bad Mags? Crap ammo (Remmy yellow box)?

I should have asked one of the gurus on Saturday, but I was having too much fun shooting my other toys....
 
I also had problems with FTF on my Stag AR...I'll go and check the BCG, but could the problem lie elsewhere? Bad Mags? Crap ammo (Remmy yellow box)?

I should have asked one of the gurus on Saturday, but I was having too much fun shooting my other toys....

Failures to feed can originate from many things alone or in combination.

Bad mags can definitely cause it, crap ammo will also if it is so under powered it won't overcome the buffer spring with a heavy buffer. Remington Yellow box is notoriously known for being under powered in many calibers. I've experienced it myself with 9mm and .223.

Any binding of the BCG either in the reciever or riding over the top of the mag can cause it. This would have to do with mag feed lips being bent outward and standing high in the ejection port or mag sitting too high in mag well. You might get double feeding from bad mag feed lips as the lips won't hold the rounds in the mag with enough tension.

A clogged gas tube can also contribute but is not the likely reason on any gun that is fairly new or not fired much.

A tight chamber or poorly resized ammo(factory or reloads) will do it also.

Check one thing at a time, look for odd wear in the receiver and on the bottom of the bolt carrier and the top of the mag feed lips, then by changing ammo, then eliminating one mag at a time.
 
I also had problems with FTF on my Stag AR...I'll go and check the BCG, but could the problem lie elsewhere? Bad Mags? Crap ammo (Remmy yellow box)?

I should have asked one of the gurus on Saturday, but I was having too much fun shooting my other toys....

FTF could be the result of bad mags (try the magpul enhanced followers). Or it could very well be ammo related.
 
I also had problems with FTF on my Stag AR...I'll go and check the BCG, but could the problem lie elsewhere? Bad Mags? Crap ammo (Remmy yellow box)?

I should have asked one of the gurus on Saturday, but I was having too much fun shooting my other toys....

How close are you to Exit 2 off the pike? I live in south Berkshire county - right off exit 2 and would be glad to host you at my range for some shooting and eval...
 
Back
Top Bottom