Index pin. barrel on - barrel off?

AR/M4 AR Technical Discussion
1

I recently had a semi-local gunsmith install a rail on a LE6920 and for reasons I’m not going in to I stopped him after he removed the barrel nut. He clamped the barrel in copper padded vice jaws and it took 15 minutes of grunting and repositioning the barrel in the vice to remove the nut. WOW! Gathered my parts. Payed him $15 and left. When I got home I noticed the barrel index pin was bent.

Maybe someone can tell me if this happened during removal or if Colt boogered my toast during installation. I’ve read about using side cutters to remove the pin but didn’t work very well for me.

2

That pin is bent in the direction of torqing ON the nut. If Rosco was turning the nut the wrong way, he could have done this.

On the other hand, I’ve pulled factory Colt nuts off that had over 100 ft/lb of torque to break them free. How does the upper’s notch look???

3

Mark, How could Bubba have done it if he was holding the barrel in a vise?

4

“How does the upper’s notch look???”

5

The upper looks fine. I’d have no issue using the barrel either. If you are keeping the FSB. Loosely install the barrel and see if it looks canted or not. If it’s not, reassemble. Mark is correct, that pin was bent on installation and I’ve had several manufacturer’s barrels take more than 100 ft/lbs to remove the nut.

6

The indexing pin notch looks better than I expected.

At minimum you need a new index pin, but if the hole for the index pin is egged out you will need a new barrel.

Never clamp the barrel or use a Reaction Rod to loosen a barrel nut.

7

If you decide to toss the barrel due to an egged out index pin hole, send it to me and I’ll use it.

8

Shouldn’t have been able to, but you never know what a Bubba can do.

9

I’ve used the Reaction Rod before… but never on a Colt Factory nut. I’d probably borrow Pappabear’s receiver block if I had to do this in the future.

10

The Midwest reaction type rods with the square top that engages the track in the upper receiver are the shit.