Uh oh, pistol grip hex head screw broke off (AR 10)

[Ranger Roberts]

So I was putting together an AR 10 lower that has just been sitting in my safe. I've assembled many lowers of the years with no problems at all. I was in the home stretch and putting my pistol grip handle on. As I was turning the hex head screw, I felt that it was a little gritty. Instead of unscrewing it and spraying brake cleaner in, I was lazy and backed it out a few turns then tightened it back up. I realized that the hex head screw was a little long and I was going to have to put a washer in so it can snug up. No go! The dang thing wouldn't budge. I sprayed some liquid wrench in, waited a few minutes, tried again and snapped the head off! :banghead: No big deal, I took a file to what was left, squared it up, put vice grips on it, gave it a turn... nothing. I can't get it to budge.
Any suggestions on getting this thing out? I have a set of "spiral fluted screw extractors" but have never used them before. Do they work well? Any ideas or suggestions would be greatly appreciated. Thanks all!
My laziness really bit me in the butt this time!

 

[Acera]

For the next time, I would not consider using brake cleaner when what you need to use is a tap and oil to chase the threads. Break cleaner would remove any helpful lubrication you may have had in there.

If you can still get vice grips on it, you stand a better chance than those screw extractors.

Take a picture and post that up.

 

[The Bushmaster]

Drill and tap to one size larger and try again.

 

[Ranger Roberts]

For the next time, I would not consider using brake cleaner when what you need to use is a tap and oil to chase the threads. Break cleaner would remove any helpful lubrication you may have had in there.

If you can still get vice grips on it, you stand a better chance than those screw extractors.

Take a picture and post that up.

I didn't think about that with the brake cleaner, that is a very good point. Thanks, I will definitely use oil next time.

I kept trying the vice grips to no avail. I can take file to the stud again and see if I can get a good grip.

I'll take a pic as soon as I get home. Thank you!

Drill and tap to one size larger and try again.

I think that is what is going to end up happening. I was going to try to exhaust my other possibilities first.

 

[edwardware]

Before you drill and tap. . . oil well, and heat the aluminum.

I'd use a propane torch, gently, and try to move the bolt as the aluminium warms up.

 

[Ranger Roberts]

Before you drill and tap. . . oil well, and heat the aluminum.

I'd use a propane torch, gently, and try to move the bolt as the aluminium warms up.

Awesome, I will give that a try as soon as I get home. Thanks!

 

[Wireman]

The original configuration used a shorter bolt. Then newer grip types and some aftermarket trigger modifications were introduced which required the longer bolt. The longer bolt almost always requires running the tap all the way into the receiver, since the early lowers did not have threads all the way through. I would cut off the plastic grip with a dremel saw giving you access to the bolt on the bottom side. With the grip cut off, there might be enough metal there to grab with vice grips. Otherwise, use diamond burrs on the dremel to slowly eat away the center of the bolt.

WM

 

[maxxhavoc]

I have had this happen twice.

#1 had a good bit of bolt sticking out of the receiver. I put a nut over it, welded the nut to the bolt, and got it out.

For #2, there wasn't enough bolt sticking out, and building the weld into the nut didn't work. Not sure what the bolt was made out of, but good steel it wasn't. I drilled out the bolt from the top (so I could use a RH twist bit, and it was easier to center since I could tape the bit out to the ID of the receiver.) I got it close enough to centered to make it so there was no real damage to the threads. I stepped up a couple sizes of bit, one caught, and unscrewed it. If you have a press and LH bits, the same will work from the bottom. Just make sure the bit is centered.

From then on, EVERY receiver gets a tap run through it.

 

[Acera]

Ranger Roberts, use that penetrating oil liberally before your next attempt.

Did you notice if the bolt threads had a locking compound on them before you tried to install it?


Good Luck,

 

[Ranger Roberts]

Ranger Roberts, use that penetrating oil liberally before your next attempt.

Did you notice if the bolt threads had a locking compound on them before you tried to install it?

I will use a lot more penetrating oil this time around. I didn't appear to have any thread lock. My suspicion is that a sliver of metal from either the bolt or the receiver wedged into the thread.

#1 had a good bit of bolt sticking out of the receiver. I put a nut over it, welded the nut to the bolt, and got it out.

I've done this before but never on a lower receiver. I'm a decent welder but my brother does it professionally, maybe I can have him take a look.

 

[Kp321]

If you take your time and carefully drill, you can probably get the broken bolt out without messing up the receiver threads. If not, don't go oversize, have it Helicoiled back to original size.

 

[Hookeye]

Kroil.
Let it set for a while, then heat.
Add more when it cools and then try to unscrew it.
May try cutting a slot in bolt body with dremel for screwdriver blade.

 

[Ifishsum]

EVERY receiver gets a tap run through it.

That's what I do as well. Many lowers are not threaded all the way so you must be careful about bolt length..so the first thing I do before starting a lower is run a 1/4x28 tap all the way through.

 

[FROGO207]

Use bees wax to lube the aluminum when you tap it. This will prevent it from galling on the tap. If there is no Loc-Tite to be used you can lube the screw/bolt with it as well. I tapped and assembled hundreds of sailboat masts with rigging at various boatyards on this island with only about two broken taps over the coarse of 10 years. The bees wax works well.

Yes if you can get the Vise Grips on the broken end, then heating the aluminum moderately will often allow the screw to move when the aluminum expands.

 

[Acera]

R R you get it fixed yet??

If so, what worked for you??

 

[Ranger Roberts]

I finally fixed it yesterday. So I tried a variety of different things to get it fixed. I soaked the stud in liquid wrench for hours and tried wrenching it off with vice grips. I used a butane pen to heat the aluminum (under the grip, it won't be seen) and tried vice grips. My brother insisted on cutting a slot in the stud and using a flat head screw driver on it to try to loosen it that way, no luck.
What we ended up doing was cutting the stud flat to the receiver. Then we started drilling. We stepped up the bits until we could almost see the threads. Then we started collapsing the metal on itself with a tiny screw driver and blowing the shavings out. Eventually we were able to tap it to the original 1/4 x 28 threading. It worked great. I'm pleased with the outcome. And I learned my lesson about running a tap through it BEFORE I dry fit that bolt!
Thanks for all the help guys. It is very much appreciated!