Grip thread not tapped correctly?

[Funkenstein]

I just built a lower for a buddy on a Aero Precision "Second Amendment" stripped lower. Everything fit great until I got to the grip.

I used a Magpul MOE grip with the included Magpul stamped bolt.

I started screwing it in and got hard resistance about 3 turns in. I backed it out before trying to muscle it, thinking I may have it at a slight angle. This occurred 3 more times....

I took the grip off and just screwed the bolt in with the lower on a block and same thing.

I finally decided to just muscle it on and I could clearly hear a metal cutting sound. It was threading itself with the screw. I took it out and cleaned it, getting some metal shavings each time.

I continued this till I was close to where it was "supposed" to be and threw a washer on it.

I tested it by pulling and cranking on the grip after it was installed and it doesn't budge a mm.

Just wonder if anyone has had this issue, and if I should bring it up to Aero Precision.

Thanks,

-Funk

[GH41]

You should have contacted Aero before you posted per forum rules. There is a good chance the grip wasn't aligned properly before you tightened the screw and you cross threaded it. You should have figured this out before trying 2 more times! Fastener rule #1... DON'T force threaded fasteners.

[Funkenstein]

You should have contacted Aero before you posted per forum rules. There is a good chance the grip wasn't aligned properly before you tightened the screw and you cross threaded it. You should have figured this out before trying 2 more times! Fastener rule #1... DON'T force threaded fasteners.

In hindsight you are right. Luckily it's not a "functioning" piece and I don't think it will back out at all.

I am pretty positive I didn't cross thread it because I didn't apply any pressure when I got the initial resistance. I made sure it was aligned every time I retried.

I think it was a combination of a rookie mistake and my buddy breathing down my neck to get it done.

Thanks for the reply.

[ucrt]

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Did you try another 1/4-28 screw? Could be a wrong screw.

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[Hkbeltfed]

Did the Magpul bolt have their usual 'way too much, way to hard' yellow thread locker on it?

[Funkenstein]

Did the Magpul bolt have their usual 'way too much, way to hard' yellow thread locker on it?
It did, however it was only on the upper half of the bolt near the bolt head. I was running into issues well before I reached the yellow mass ha.

[dramabeats]

In hindsight you are right. Luckily it's not a "functioning" piece and I don't think it will back out at all.

I am pretty positive I didn't cross thread it because I didn't apply any pressure when I got the initial resistance. I made sure it was aligned every time I retried.

I think it was a combination of a rookie mistake and my buddy breathing down my neck to get it done.

Thanks for the reply.

Shavings + resistance usually means you cross threaded it.

Have you ever worked on a car?

[AKDoug]

On every lower I run a tap through that hole. On every Magpul grip I run the screw through a die to remove the loktite from it. I then use my own blue loctite and assemble.

[Just Prince]

You can always re-tap it with a tap and die set.

[sevenhelmet]

Ouch! It's definitely cross-threaded. Based on your description, I'm not even sure re-tapping the threads will help. You just did a bubba fit on your buddy's gun. I sure hope it holds up...

[friendlyfireisnt]

This is why when installing the grip, I always check the screw in the hole prior to installing the grip. That way I make sure there is no interference, and I have a baseline for how much force I need to use.

The magpul loctite can be an issue as well, but I often just heat it with a match prior to install.

[NickySantoro]

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Did you try another 1/4-28 screw? Could be a wrong screw.

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My first thought also.

FWIW, OP, if you have to muscle it, STOP and revisit each possibility. Something's wrong.

[Hmac]

I doubt that you're cross-threaded and I doubt that your threads are bad. Magpul grips are notorious for this problem. With Magpul grips, I have taken to heating the grip screw with a butane torch enough to melt the yellow threadlocker and then clean it off, replace with blue, or a star washer. I've thought I had stripped the receiver on at least a couple of occasions. Getting rid of their threadlocker or using a different screw has never failed to solve the problem.

[tigershilone]

my buddy breathing down my neck to get it done.

Thanks for the reply.

What type of quality do you want to put out? Would you have done this on your own rifle?

Either the threads on the screw were bad or there was debris in the receiver or the receiver did not have full threads (seen all three before). Best practice would have been to run another 1/4-28 bolt to see if problem was the bolt or the receiver. I run a chaser tap to clear threads if I have problems, a chaser tap does not cut the existing threads further unless there is damage which it usually clears. Using a normal tap has the potential of cutting more material out and dropping the threads a class fit---but to be fair I have used a regular tap before as well.

Sometimes there is no hope for the existing threads. In that worst case you will need to install a 1/4-28 helicoil repair kit http://www.amazon.com/Helicoil-5528-4-0-25-28-Thread-Repair/dp/B000QFRUCA that will completely drill out the old threads and install new stainless threads in their place. Be fore-warned that installing helicoils is not a job for the in-experienced, but if properly installed are stronger than the original threads. If it is a forged 7075T6 aluminum receiver or even a 6061T6 then both materials will take helicoil repairs very well.

In any repair event, the receiver would need to have the FCG and safety selector assy's removed at the minimum.

If you really have it torqued all the way up in there really good and it's cross-threaded then it's probably best to leave it alone if it is secure. Once it is backed out I wouldn't trust it to be secure ever again as the threads are probably galled now and will require a repair.

Good luck with this, let us know how it turns out.

[Funkenstein]

What type of quality do you want to put out? Would you have done this on your own rifle?

Either the threads on the screw were bad or there was debris in the receiver or the receiver did not have full threads (seen all three before). Best practice would have been to run another 1/4-28 bolt to see if problem was the bolt or the receiver. I run a chaser tap to clear threads if I have problems, a chaser tap does not cut the existing threads further unless there is damage which it usually clears. Using a normal tap has the potential of cutting more material out and dropping the threads a class fit---but to be fair I have used a regular tap before as well.

Sometimes there is no hope for the existing threads. In that worst case you will need to install a 1/4-28 helicoil repair kit http://www.amazon.com/Helicoil-5528-4-0-25-28-Thread-Repair/dp/B000QFRUCA that will completely drill out the old threads and install new stainless threads in their place. Be fore-warned that installing helicoils is not a job for the in-experienced, but if properly installed are stronger than the original threads. If it is a forged 7075T6 aluminum receiver or even a 6061T6 then both materials will take helicoil repairs very well.

In any repair event, the receiver would need to have the FCG and safety selector assy's removed at the minimum.

If you really have it torqued all the way up in there really good and it's cross-threaded then it's probably best to leave it alone if it is secure. Once it is backed out I wouldn't trust it to be secure ever again as the threads are probably galled now and will require a repair.

Good luck with this, let us know how it turns out.
Like I said, in hind sight it was a bad decision. But it is tight and not budging so we decided to leave it. If anything changes I will look into the repair.

Thanks