How easy is it to cross thread the pistol grip screw?

[Hoss356]

Didn't even know about them at the time. I would consider it now if I had to fix one again, but I'm still not sure I trust them that much. I read at least one account (I believe it was in this forum) of the heli-coil stripping out of a billet lower. My fix was low-tech, but it worked.

Actually drilling and re-threading (re-tapping) is the proper way to repair a stripped screw hole, heli-coil is the low tech bandaid fix.




As for that stupid balancing act with the normal grip screw, I took one look at that and thought f--k that. The first thing I did, when I starting building my lower was to throw away the screw that came with the grip and picked up an allen head bolt. Anytime I've taken the grip off since it's been very easy to chase down the threads since the screw stays on the allen wrench with out wobbling.

[rob_s]

As for that stupid balancing act with the normal grip screw, I took one look at that and thought f--k that. The first thing I did, when I starting building my lower was to throw away the screw that came with the grip and picked up an allen head bolt. Anytime I've taken the grip off since it's been very easy to chase down the threads since the screw stays on the allen wrench with out wobbling.

Funny you should mention that, as I've removed every allen-head screw from every AR I've ever had that came with one.

If you read through thread and between the lines you'll see that the real issue here is a combination of non-spec parts/problems. You have a lower that is notorious for having too-tight grip screw threads/holes and a screw that's notorious for having entirely too much loctite pre-treatment.

The right way to do this is to have a hole that is in-spec and a screw with no pre-dried thread locker on it. When you have the right combination you can easily use the correct flathead screw.

The inclusion of the allen-head screw in many lesser brands of ARs is indicative of what happens when the egg-heads start making decisions, and often those decisions are a reaction to shitty decisions beforehand (like making the hole too tight or putting too much glue on the screw).

[Quib]

Actually drilling and re-threading (re-tapping) is the proper way to repair a stripped screw hole, heli-coil is the low tech bandaid fix.

I would consider the heli-coil superior and more permanent of a repair than simply up-sizing the hole and re-threading. The heli-coil being stainless steel and if installed correctly, is stronger than threads cut into the aluminum.

We use heli-coils extensively in aviation.

[Alex V]

I would consider the heli-coil superior and more permanent of a repair than simply up-sizing the hole and re-threading. The heli-coil being stainless steel and if installed correctly, is stronger than threads cut into the aluminum.

We use heli-coils extensively in aviation.

I agree. I have used it also in a drag racing aplication. I cross threaded a header bolt into an aluminum head. Used Helecoil, never had a header leak in hundreds of track passes and many years.

I think it would have been the better choice for a fix.

[Toonces]

Originally Posted by Hoss356
As for that stupid balancing act with the normal grip screw, I took one look at that and thought f--k that. The first thing I did, when I starting building my lower was to throw away the screw that came with the grip and picked up an allen head bolt. Anytime I've taken the grip off since it's been very easy to chase down the threads since the screw stays on the allen wrench with out wobbling.

99.9999% of the time, the allen-head screws are better, I don't think many people would argue that. Or maybe I should say that flathead screws suck if you don't have a proper fitting, hollow ground screwdriver. But when SHTF, a dime store flat screwdriver will work. Good luck finding an allen wrench, let alone the right size. For most normal people, the probablility of needing to remove the grip under pressure is so minute that it probably doesn't matter. For the guys that go into harm's way on purpose, why risk needing such a specialized tool?

Funny you should mention that, as I've removed every allen-head screw from every AR I've ever had that came with one.

If you read through thread and between the lines you'll see that the real issue here is a combination of non-spec parts/problems. You have a lower that is notorious for having too-tight grip screw threads/holes and a screw that's notorious for having entirely too much loctite pre-treatment.

The right way to do this is to have a hole that is in-spec and a screw with no pre-dried thread locker on it. When you have the right combination you can easily use the correct flathead screw.

The inclusion of the allen-head screw in many lesser brands of ARs is indicative of what happens when the egg-heads start making decisions, and often those decisions are a reaction to shitty decisions beforehand (like making the hole too tight or putting too much glue on the screw).

It sounds to me like some manufacturers are forgetting to account for the thickness that anodizing adds. I would bet those holes gage ok before anodizing, but are on the tight end of ok. Even though it's hard to get the same amount of anodizing inside a small hole as on an exterior surface, there is enough to make problems, as seen in this thread.

I've seen this more than a few times as I've been standing between the machine operators and the inspectors. The operators don't care because it gaged ok when they made it. The inspectors think the operators are dumb because the finished part fails final inspection. The person who needs to be educated is the manufacturing engineer/setup guy. If he orders the proper combination of taps and gages from the start(more than one way to skin a cat), this problem goes away.

By the way, anodizing is not as simple as it looks (for production parts with tighter tolerances). The merely ok shops will make your life miserable, and the good shops cost $$$. Guess which one gets picked most often, at least until the cost of the problems exceeds the price differential?

I would consider the heli-coil superior and more permanent of a repair than simply up-sizing the hole and re-threading. The heli-coil being stainless steel and if installed correctly, is stronger than threads cut into the aluminum.

We use heli-coils extensively in aviation.

At my previous job we built aluminum transmissions for 1000-2000 hp marine applications and a couple of military vehicles. The important load carrying joints were designed to use heli-coils to reduce assembly mishaps and prevent thread problems when repeatedly assembling/removing items.

[ST911]

We use heli-coils extensively in aviation.

In heli-copters, too?

Badump-ching.

Nevermind.

[Hoss356]

I would consider the heli-coil superior and more permanent of a repair than simply up-sizing the hole and re-threading. The heli-coil being stainless steel and if installed correctly, is stronger than threads cut into the aluminum.

We use heli-coils extensively in aviation.

You have a point, I didn't take into account the aluminum, but making the hole bigger is also going to increase the thread contact, the heli-coil is still grabbing the aluminum through. Now that I think about it the heli-coil is grabbing what's left of the threads and has an interference fit like a drywall anchor so I can see why it could have a higher load rating.

I'm just not used to using them unless their the only fix available, but I also don't work with aluminum alot.

So with all that said, my new position is either fix will be stronger than it was before due to the increased screw size and thread contact with re-tapping or the multiple forces securing a heli-coil in. Unless my logic is flawed here to? I think college is melting my brain.

[Quib]

In heli-copters, too?

Badump-ching.

Nevermind.

LOL.....oh yea, in helicopters too.

[TheDude]

All good answers. I am gonna first try the low tech approach and strip the loctite off. then if that doesnt work I will try the tap. Where would I get one of those jammies.

I guess I should also mentioned I tried Rompa room company's screw and that was a pain in the ass too!

[Quib]

............. if that doesnt work I will try the tap. Where would I get one of those jammies.

I’ve purchased individual taps at ACE Hardware.