PDA

View Full Version : over torqued barrel


evilmonkey
11-30-08, 22:31
So I was putting my barrel on my upper the other night and I over torqued it and the little part that sticks up from the barrel extension that lines up the upper and the barrel sheared off. Any fixes for this? I was thinking about JB welding that piece on but didnt know how it would hold up. Any suggestions please!
scottryan
11-30-08, 22:37
How can you over torque your barrel and break the index pin?

You are putting torque on the barrel nut, the index pin is suppose to have very little force on it.

All the force is the longitudinal clamping force cause by the barrel nut / receiver interface.
evilmonkey
11-30-08, 22:50
I have no idea to be honest! I hand tightened it then put a little torque on the wrench and the thing sheared off! Ive but 3 barrels on and have never had this happen! I didnt even put that much force on it just a quick turn and the upper was a little crooked took it back off and it was sheared off
MisterWilson
11-30-08, 22:53
I'm thinking that maybe the pin wasn't in it's groove and he kept on going.

So can I call dibs on the AR tools he's about to (or should be) selling?
Iraqgunz
12-01-08, 00:39
Evil,

I am unsure as to what to say. The upper receiver is aluminum and that pin is steel. You must have really rented a 400 lb. gorilla or the barrel extension is crap. Either way I would recommend that you purchase a new barrel extension and have it installed, and then the have them install the barrel into the upper.
mark5pt56
12-01-08, 14:39
Reference the index pin, the RRA 9mm barrel I got one time had a pin issue. It fell out and was really short, I would say that maybe his was not in spec, even weak material.

Or--gotta change your handle to evilgorilla!:eek:

I don't know, but I would guess you could remove the pin and get a new one in there? See if the manufacturer could send you one, a good Smith should be able to help get the old one out.
scottryan
12-01-08, 15:33
Evil,

I am unsure as to what to say. The upper receiver is aluminum and that pin is steel. You must have really rented a 400 lb. gorilla or the barrel extension is crap. Either way I would recommend that you purchase a new barrel extension and have it installed, and then the have them install the barrel into the upper.


Barrel extensions cannot be swapped.
Iraqgunz
12-01-08, 15:44
Though I have never done it, I have been told that they can be removed. So you are saying that it isn't possible?


Barrel extensions cannot be swapped.
blacktail 8541
12-01-08, 17:39
Barrel extentions can be repaced but it is a major headache. send it to ADCo or another compatent shop to have the pin replaced
scottryan
12-01-08, 18:26
A barrel extension is fitted to each barrel just like a front sight base.

They cannot be replaced without major rework that gives you a non factory barrel in the end.
evilmonkey
12-01-08, 19:57
So I guess a dab of JB weld wouldnt fix it? Is there a lot of pressure against that piece?
BretShooter
12-01-08, 20:36
So I guess a dab of JB weld wouldnt fix it? Is there a lot of pressure against that piece?

The point isn't the pressure, it is whether or not the head space has changed or was even right in the first place, given that the pin was so loose it fell out. The barrel is suspect, and should be returned to the manufacturer/distributor and replaced. It isn't the armorer's fault.

If you can check the headspace, and can tell that the pin wasn't in deep enough, and is the hole IS deep enough (thru the extension and into the barrel far enough for the pin to stick up just enough to index the barrel, but not interfere with the barrel nut threads) and still lined up, one could be confident that the extension could be re-pinned as is.
evilmonkey
12-01-08, 20:45
How would you remove the pin? Would I have to take out the extension or could I just re-pin it as is?
BretShooter
12-01-08, 20:54
I wouldn't remove the pin. You should not remove the extension. Seriously, don't. If you do, it won't line up right, tight and properly headspaced at the same place.

You said your pin came out. Does the pin hole extend thru the extension and into the barrel abit? Is it a clean, straight hole and both parts are still lined up?

Are you using a receiver vice or a barrel vise when installing the barrel? The only way I can see any excessive force applied against the pin would be with a barrel vise.
evilmonkey
12-01-08, 21:20
It sheared off! the other half is still in the barrel! the piece in the barrel is flush with the barrel
Robb Jensen
12-01-08, 21:29
It sheared off! the other half is still in the barrel! the piece in the barrel is flush with the barrel

Have a machine shop or the barrel manufacturer remove the broken of the pin out of the barrel, replace it and soldier on. Be sure to use an upper receiver block when installing a barrel.
scottryan
12-01-08, 22:28
It sheared off! the other half is still in the barrel! the piece in the barrel is flush with the barrel




I still think your barrel is suspect. This should not break off.

What brand is it?
BretShooter
12-01-08, 23:03
I still think your barrel is suspect. This should not break off.

What brand is it?

+1

If it were a proper pin, I would say that it couldn't. Roll pins can take a lot of punishment, and I have never heard of one shearing by force applied via an aluminum part.