Need help with AR pistol.

[klewan]

After reading this thread a couple of times, it still doesn't make any sense. Only way to get the extension to unscrew is the barrel has to be able to rotate and the extension is being held stationary by the bcg. The extension doesn't touch the inner surface of the upper I'm looking at.

Then being able to rotate the barrel; you have the pin driven into a hole on the barrel and then indexed into a slot on the upper. So you either shear the pin or tear the end of the upper to pieces by rotating it. But you have a barrel nut that is pressing the barrel flange up against the end of the upper with some serious torque. So that by itself should keep the barrel from rotating. Even without a pin.

Only way this makes sense is the bcg was installed, barrel nut was loose but not completely off. That allowed the pin to leave the slot and let the barrel rotate. The extension was not torqued to spec or anywhere near it. So the extension was held while the OP was rotating the barrel trying to get the brake off. I played around with my parts and the bcg won't let the barrel move forward more than about .125", which is almost enough so it will let the barrel rotate, but the pin is still about .020" into the slot. So if it rotates, it tears up the threaded end of the upper. Or if there wasn't a pin installed to begin with, then it rotates if the barrel nut isn't tight.

So there were two problems; the barrel extension and barrel nut had to be loose for this to happen. OP?

[kcstott]

After reading this thread a couple of times, it still doesn't make any sense. Only way to get the extension to unscrew is the barrel has to be able to rotate and the extension is being held stationary by the bcg. The extension doesn't touch the inner surface of the upper I'm looking at.

Yeah it does. it has to if the barrel nut is tight.

Then being able to rotate the barrel; you have the pin driven into a hole on the barrel extension and then indexed into a slot on the upper. So you either shear the pin or tear the end of the upper to pieces by rotating it. But you have a barrel nut that is pressing the barrel extension flange up against the end of the upper with some serious torque. So that by itself should keep the barrel from rotating. Even without a pin.

Only way this makes sense is the bcg was installed, barrel nut was loose but not completely off. That allowed the pin to leave the slot and let the barrel rotate. The extension was not torqued to spec or anywhere near it. So the extension was held while the OP was rotating the barrel trying to get the brake off. I played around with my parts and the bcg won't let the barrel move forward more than about .125", which is almost enough so it will let the barrel rotate, but the pin is still about .020" into the slot. So if it rotates, it tears up the threaded end of the upper. Or if there wasn't a pin installed to begin with, then it rotates if the barrel nut isn't tight.

You don't understand the parts involved with assembling a barrel from scratch.
You do know the barrel extension threads onto the barrel correct??
there are female threads on the extension and male threads on the barrel. we are just always use to seeing a complete barrel

So there were two problems; the barrel extension and barrel nut had to be loose for this to happen. OP?

Nope just the extension. Because the barrel pin is only located in the barrel extension and is not in the barrel threads.

Think about it if the barrel extension was installed but never torqued the barrel pin and nut can be properly located and torqued. But the barrel could be threaded in and out of the extension with no issues.

the reality is this reeks of troll thread as the gas tube and block would need to be removed for this to occur even with a loose barrel extension. and why the hell would you remove the gas block and gas tube to install a new muzzle brake??

[klewan]

Yeah it does. it has to if the barrel nut is tight.




You don't understand the parts involved with assembling a barrel from scratch.
You do know the barrel extension threads onto the barrel correct??
there are female threads on the extension and male threads on the barrel. we are just always use to seeing a complete barrel





Nope just the extension. Because the barrel pin is only located in the barrel extension and is not in the barrel threads.

Think about it if the barrel extension was installed but never torqued the barrel pin and nut can be properly located and torqued. But the barrel could be threaded in and out of the extension with no issues.

the reality is this reeks of troll thread as the gas tube and block would need to be removed for this to occur even with a loose barrel extension. and why the hell would you remove the gas block and gas tube to install a new muzzle brake??

My mistake; when you insisted the pin is in the extension, I got my Glen Zediker AR book and looked for barrel photos. Found one of the extension and even the flange is part of it. Went out and looked at my barrel, there is an obvious seam just past the pin, that is what I mistook for the extension. Had to use the magnifying lenses to see the seam at the flange. So the pin is what held the barrel stationary, that I can see now.

[kcstott]

My mistake; when you insisted the pin is in the extension, I got my Glen Zediker AR book and looked for barrel photos. Found one of the extension and even the flange is part of it. Went out and looked at my barrel, there is an obvious seam just past the pin, that is what I mistook for the extension. Had to use the magnifying lenses to see the seam at the flange. So the pin is what held the barrel stationary, that I can see now.

Like I said we are use to seeing complete barrels.

the only guy here that buys barrel extensions on a regular basis is Randal. I've done a hand full of AR barrels from scratch. Not fun and not cheep to do. Randal has his process dialed in to the point he can do it pretty quick.

Go over to my web sight and down load the print for the barrel and the barrel extension it will become completely obvious

[ar15barrels]

why the hell would you remove the gas block and gas tube to install a new muzzle brake??

He said he removed them once he noticed they were all turning.

[ar15barrels]

You don't understand the parts involved with assembling a barrel from scratch.
You do know the barrel extension threads onto the barrel correct??
there are female threads on the extension and male threads on the barrel. we are just always use to seeing a complete barrel

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[ar15barrels]

My mistake; when you insisted the pin is in the extension, I got my Glen Zediker AR book and looked for barrel photos. Found one of the extension and even the flange is part of it. Went out and looked at my barrel, there is an obvious seam just past the pin, that is what I mistook for the extension. Had to use the magnifying lenses to see the seam at the flange. So the pin is what held the barrel stationary, that I can see now.

Barrel extensions OFF the barrel:

Went out and looked at my barrel, there is an obvious seam just past the pin, that is what I mistook for the extension.
Had to use the magnifying lenses to see the seam at the flange. So the pin is what held the barrel stationary, that I can see now.

No mistake.
The EXTENSION is the part with the locking lugs, the flange and the indexing pin.
The BARREL is the part with the chamber and rifling.
The BARREL screws into the EXTENSION.
The EXTENSION is retained within the receiver by the barrel nut.

[gunrus]

I got my ar pistol back from the vendor. It's all put back together. Should I go ahead and get a barrel vise or test out the torque?

[kcstott]

Well I would but thats just me, Depending on the vendor and what kind of reputation they have outside of this situation would determine how much scrutiny i put on the fix

[gunrus]

Well I would but thats just me, Depending on the vendor and what kind of reputation they have outside of this situation would determine how much scrutiny i put on the fix

You would test the torque? Thanks

[kcstott]

well I mean don't try to unscrew the thing and find out exactly what torque they used to put it on. but yeah given the situation I wouldn't trust them to do jack correctly,

I'd put about 50 to 80 lbs of force on it if it don't move call it good. As Randall said it should be torqued to 100+ foot lbs so putting 80 on it to try to remove it will not move a properly torqued barrel extension. It always takes a bit more torque to remove something then it did to put it on, so in this case if it was torqued to 100ft/lbs on the button, it would need 150 to break it loose. and you don't want to do that. you just want to check it for tightness thats it.