Grip Screw Troubles

[Califpatriot]

I bought a used AR via PPT. It had a standard Magpul MOE grip (it's a fixed mag design). I wanted to change out the trigger to a 2-stage, so I took my 3/16 t-handle hex key, unscrewed the magpul-branded grip screw with no problem, took out the safety, the FCG, put in the new FCG, replaced the safety, put the detent, detent spring, and Magpul MOE grip back in. All good. Then I start screwing the same Magpul grip screw back in with the T-handle and it starts to encounter resistance almost immediately. I unscrew and try again to make sure I'm doing it at the correct angle and with a LOT of force get it to screw ALMOST all the way in--but not entirely. It goes in about 70-80% of the way when I'm encountering a ton of resistance, and then it makes a sound and when I try to turn the screw, the hex key just spins.


So what happened? Did I strip the grip screw head? It doesn't look like it--that thing looks extremely solid, and doesn't look stripped. Did I strip the hex key? Possible, but why was it so hard to thread it in? Was the grip screw hole stripped? Moreover, what do I do about the screw that's now stuck halfway inside the grip, and how do I get it all the way in, or at least out?

[ar15barrels]

I bought a used AR via PPT. It had a standard Magpul MOE grip (it's a fixed mag design). I wanted to change out the trigger to a 2-stage, so I took my 3/16 t-handle hex key, unscrewed the magpul-branded grip screw with no problem, took out the safety, the FCG, put in the new FCG, replaced the safety, put the detent, detent spring, and Magpul MOE grip back in. All good. Then I start screwing the same Magpul grip screw back in with the T-handle and it starts to encounter resistance almost immediately. I unscrew and try again to make sure I'm doing it at the correct angle and with a LOT of force get it to screw ALMOST all the way in--but not entirely. It goes in about 70-80% of the way when I'm encountering a ton of resistance, and then it makes a sound and when I try to turn the screw, the hex key just spins.


So what happened? Did I strip the grip screw head? It doesn't look like it--that thing looks extremely solid, and doesn't look stripped. Did I strip the hex key? Possible, but why was it so hard to thread it in? Was the grip screw hole stripped? Moreover, what do I do about the screw that's now stuck halfway inside the grip, and how do I get it all the way in, or at least out?

Sounds like you galled the screw.
Start by putting some wd-40 in the hole from both sides of the screw.
Work the screw back and forth as you unscrew it to get the wd everywhere.
Once the screw is out, chase the threads with a 1/4-28 tap.

If you can save the reciever, throw the screw away and get a new one and use some anti-seize on the threads.

[Califpatriot]

Thanks, Randall. I'll probably take it to my local gunsmith to avoid mucking it up further.

Any reason that a trained gunsmith wouldn't be able to save the receiver? (It's a very expensive one for stupid California regulatory reasons.) I figure that somebody who knows what they're doing shouldn't have much of a problem fixing the threads.

[STiLtd683]

A decent gunsmith should be able to save the receiver.

[johnthomas]

What is that, 1/4 x 18? Take it out, tap it and try it again, you put it in cockeyed. I have had that happen and this worked for me. Make sure the bolt and the thread is correct by screwing the bolt into a nut the same size, then the correct tap.

[Sparrow Dynamics]

What is that, 1/4 x 18? Take it out, tap it and try it again, you put it in cockeyed. I have had that happen and this worked for me. Make sure the bolt and the thread is correct by screwing the bolt into a nut the same size, then the correct tap.

1/4-28

[ar15barrels]

Thanks, Randall. I'll probably take it to my local gunsmith to avoid mucking it up further.

Any reason that a trained gunsmith wouldn't be able to save the receiver?

For this job, machinist experience will be more important than any sort of gunsmith training.

the absolute worst case is that it has to be drilled out and then a helicoil installed to create new threads.

[SkyHawk]

You may have to saw the grip off to get to the screw with pliers or something. Are you sure the shank of your T-handle hex tool is not spinning at the handle?

Should have never used "a lot" of force. Nothing good will come from running a steel bolt into aluminum thread hole with a lot of force required. And at the first sign of trouble I would have taken the grip off and examined the hole and tried to run the bolt in by hand without any grip in place.

Ah well, water under the bridge now. I hope you get it sorted out.

[Steelplate45]

I have found the hard way, that it is possible to cross-thread an AR grip screw. Same symptoms you mention. Sounds like you went too far to fix it with a thread chaser. So, machinist help and heli-coil will solve it, as mentioned by others.

[ar15barrels]

Nothing good will comes from running a steel bolt into aluminum thread hole with a lot of force required.

[Califpatriot]

For this job, machinist experience will be more important than any sort of gunsmith training.

the absolute worst case is that it has to be drilled out and then a helicoil installed to create new threads.

Can you do it? I'd be happy to ship it to you. PM me the price, but I'm sure it's reasonable.

[ar15barrels]

Can you do it? I'd be happy to ship it to you. PM me the price, but I'm sure it's reasonable.

I can't accept firearms through the mail.
If you were local and made a walk-in appointment, I could do it while you wait.

[Califpatriot]

Ok, thanks. I have a local gunsmith I trust I'll go to this week check it out; if he's unable to do it, I'll see if we can set up a time next time I'm in LA for business. Thanks.

[ozarkpugs@gmail.com]

If you know a good auto or small engine mechanic they work with stripped /cross threaded screws all the time.

Sent from my Moto E (4) using Tapatalk

[Califpatriot]

Gunsmith fixed it in about five minutes. Took a ratcheting driver to it, got the screw out, retapped it and put a new screw in. Didn't have to cut off the grip even.