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strat81
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Posted: 6/22/2009 9:17:45 AM
[Last Edit: 6/23/2009 12:15:18 PM by strat81]
What size is the pistol grip screw? Length, thread pitch, etc?
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osprey21
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Posted: 6/22/2009 9:32:49 AM

Originally Posted By strat81:
What size is the pistol grip screw? Length, thread pitch, etc?

1/4-28x1" socket head cap screw.
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strat81
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Posted: 6/22/2009 9:34:43 AM
Originally Posted By osprey21:

Originally Posted By strat81:
What size is the pistol grip screw? Length, thread pitch, etc?

1/4-28x1" socket head cap screw.


Is there any benefit to using a hex screw over a slotted?

Part of the reason I'm asking this is because while switching grips, I FUBARed a hex head screw.
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NotDeaf
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Posted: 6/22/2009 9:38:38 AM
I think its up to you what you want to use.

I'm sure that a "good" hareware store would have a hex head screw
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osprey21
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Posted: 6/22/2009 9:41:30 AM

Originally Posted By strat81:
Originally Posted By osprey21:

Originally Posted By strat81:
What size is the pistol grip screw? Length, thread pitch, etc?

1/4-28x1" socket head cap screw.


Is there any benefit to using a hex screw over a slotted?

Part of the reason I'm asking this is because while switching grips, I FUBARed a hex head screw.

For me, a hex head is far easier to use than a slot head.

YMMV

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strat81
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Posted: 6/22/2009 9:46:33 AM
Originally Posted By osprey21:

Originally Posted By strat81:
Originally Posted By osprey21:

Originally Posted By strat81:
What size is the pistol grip screw? Length, thread pitch, etc?

1/4-28x1" socket head cap screw.


Is there any benefit to using a hex screw over a slotted?

Part of the reason I'm asking this is because while switching grips, I FUBARed a hex head screw.

For me, a hex head is far easier to use than a slot head.

YMMV



I'm a bit of an idiot.


What's the benefit of using a 1" screw? I guess they're "stronger" than 3/4" or 1/2"?
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Stewart
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Posted: 6/22/2009 10:04:11 AM
[Last Edit: 6/22/2009 10:04:22 AM by Stewart]
The screw is 1" in length, which really has nothing to do with strength in this case.
The bolt is 1/4" in diameter with 28 threads per inch.
strat81
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Posted: 6/22/2009 10:15:27 AM
Originally Posted By Stewart:
The screw is 1" in length, which really has nothing to do with strength in this case.
The bolt is 1/4" in diameter with 28 threads per inch.


Then why not use a shorter bolt? It seems like when a company is building thousands of ARs, saving a few cents per bolt could add up.

Is a grip more likely to come off using a shorter bolt?

I'm not calling BS on you, just curious.
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USMC-Helo
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Posted: 6/22/2009 11:27:43 AM
[Last Edit: 6/22/2009 11:30:26 AM by USMC-Helo]
On the surface, it does seem a 1/2 inch screw would be more than strong enough. Don't forget it screws into aluminum threads, which are weaker, a longer steel screw would give more aluminum threads to spread the load and help prevent the threads from stripping out.

The TM has procedures for special attacments to the pistol grip (a block to keep from switching to burst/FA). So maybe the designers envisioned the screw would see a lot more service then it actually does, there an argument the longer screw would prevent less lowers from being rejected for bad threads if the screw was twice as long, i.e. half the threads could be bad and still have enough strength.

Pure speculation, the Orginal part is 1" long, its best to replace with a 1" in case there is something we don't know and there is a good reason why the designers choose for that screw to be 1" long.

Yes, the straight edge screw driver head is a pain to fish deep into the pistol grip, Torx head or Allen Head (hex) would be easier to position the screw and drive into the lower.
ftwm

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Posted: 6/22/2009 11:53:23 AM
Sticking a screwdriver into the grip is not a "pain".

I prefer the slotted panhead screws because in a pinch a screwdriver will be much easier to find than a long T-handle hex key.
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Posted: 6/22/2009 12:22:35 PM
Originally Posted By ftwm:
Sticking a screwdriver into the grip is not a "pain".

I prefer the slotted panhead screws because in a pinch a screwdriver will be much easier to find than a long T-handle hex key.


No, but guiding the screw to the hole with a hex driver is easy. I have one hell of a time getting a slotted screw into place to get it started.

strat81
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Posted: 6/22/2009 2:12:28 PM
Originally Posted By USMC-Helo:
Pure speculation, the Orginal part is 1" long, its best to replace with a 1" in case there is something we don't know and there is a good reason why the designers choose for that screw to be 1" long.

Yes, the straight edge screw driver head is a pain to fish deep into the pistol grip, Torx head or Allen Head (hex) would be easier to position the screw and drive into the lower.


I was switching a Tango Down grip from one lower to another. The TD grip includes a hex-head screw that is slightly shorter (1/8", give or take) than the CMT and DPMS LPK screws in my lowers. The TD screw also had a bit of blue threadlocker on it. The instructions said to use the included screw and they provided a long allen wrench. It's a "dome" style head rather than a cap screw.

Well, that small nub on the end of the allen wrench makes it hard to apply any force, so getting past the threadlocker on disassembly was a pain. I eventually got it out, but tore up the head in the process.

I Loctite all of my grip screws and never had that problem with slotted screws. And since TD included a shorter screw, I was wondering if that was an issue at all.

I'll cruise by the hardware store on the way home and see what they have. Last time I needed a screw (for an M1), they didn't have it. Hopefully 1/4-28x1" is more common.

I also noticed the threads in the receiver were silver, not black. I hope I didn't mangle the threads.
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GearHead_1
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Posted: 6/22/2009 2:22:42 PM

Originally Posted By osprey21:

Originally Posted By strat81:
Originally Posted By osprey21:

Originally Posted By strat81:
What size is the pistol grip screw? Length, thread pitch, etc?

1/4-28x1" socket head cap screw.


Is there any benefit to using a hex screw over a slotted?

Part of the reason I'm asking this is because while switching grips, I FUBARed a hex head screw.

For me, a hex head is far easier to use than a slot head.

YMMV


I agree on this one, much easier to put a screw on the end of a Allen wrench or socket.
ftwm

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Posted: 6/22/2009 2:22:56 PM
You can try to clean up the threads by threading something through from the top side of the receiver, if the threads are really bad you can always put a Heli-Coil in your lower.
USMC-Helo
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Posted: 6/22/2009 2:26:30 PM
Originally Posted By strat81:
...Well, that small nub on the end of the allen wrench makes it hard to apply any force, so getting past the threadlocker on disassembly was a pain. I eventually got it out, but tore up the head in the process.

I Loctite all of my grip screws and never had that problem with slotted screws. And since TD included a shorter screw, I was wondering if that was an issue at all.

I suspected that might end up being a problem with an allen head screw and using loctite. I'm glad I used the supplied straight edge screw that came with my MagPul instead of using an allen head screw. I used loctite on the screw, and just dealt with the pain of fishing the screw down and into the hole in the grip with the flat head screwdriver.

A torx head screw would take more torque than allen head, as well, they make socket wrench versions of the torx head so you can put a lot of torque on the loctite when try to get it out.

I looked for the torx head screw in the appropriate size, couldn't find it at my local hardware store.
Stewart
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Posted: 6/22/2009 3:24:01 PM
[Last Edit: 6/22/2009 3:24:35 PM by Stewart]
A holding screwdriver makes life a lot easier when it comes to intalling pistol grips with a slotted screw.
Here is one at Home Depot Klein holding screwdriver
strat81
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Posted: 6/22/2009 3:34:37 PM
Originally Posted By ftwm:
You can try to clean up the threads by threading something through from the top side of the receiver, if the threads are really bad you can always put a Heli-Coil in your lower.


Yep, I saw that during a Google search.

I'll try with a screw from the top of the receiver. If that doesn't work, I'll try a tap. And if that doesn't work, I'll use Heli-Coil. A friend of mine has a bit of experience with them, so I won't be flying completely blind.
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Righteous
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Posted: 6/22/2009 3:36:10 PM
Originally Posted By strat81:
Originally Posted By USMC-Helo:
Pure speculation, the Orginal part is 1" long, its best to replace with a 1" in case there is something we don't know and there is a good reason why the designers choose for that screw to be 1" long.

Yes, the straight edge screw driver head is a pain to fish deep into the pistol grip, Torx head or Allen Head (hex) would be easier to position the screw and drive into the lower.


I was switching a Tango Down grip from one lower to another. The TD grip includes a hex-head screw that is slightly shorter (1/8", give or take) than the CMT and DPMS LPK screws in my lowers. The TD screw also had a bit of blue threadlocker on it. The instructions said to use the included screw and they provided a long allen wrench. It's a "dome" style head rather than a cap screw.

Well, that small nub on the end of the allen wrench makes it hard to apply any force, so getting past the threadlocker on disassembly was a pain. I eventually got it out, but tore up the head in the process.

I Loctite all of my grip screws and never had that problem with slotted screws. And since TD included a shorter screw, I was wondering if that was an issue at all.

I'll cruise by the hardware store on the way home and see what they have. Last time I needed a screw (for an M1), they didn't have it. Hopefully 1/4-28x1" is more common.

I also noticed the threads in the receiver were silver, not black. I hope I didn't mangle the threads.


Long story, short version...

I purchased 3 MOE grips, they did not feel good in my hand, even though the MOE is a nice grip. Replaced the MOE's with Tango Down Battle Grips.

The screw is 1/4 X 28 X 7/8". Which is too long and needs to be dremmeled/filed/ground to have the the last few threads rounded. I did this myself.

Also... the thin 1/64" plastic/washer that comes with the screw IS NECESSARY.

The grips were purchased on EE. One grip had the factory hex head screw and worked fine. One had what appeared to be the slotted screw from a MOE grip.

I had to get the screws from Fastenal, since none of the hardware stores or home improvement stores carried this type of screw.

Ideally a 1/4 X 28 X 3/4" screw would be my choice as it should not require modification to seat deep enough to eliminate the wobble in the grip.

Without the washer there was wobble.

Good luck!



Keith_J
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Posted: 6/22/2009 4:02:51 PM
The reason you need it long is stress distribution. Because the steel is 3 times as stiff as aluminum (modulus of elasticity), shorter screws will put more of the stress on the first few threads. This can cause failure here.

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shrikefan
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Posted: 6/22/2009 4:29:59 PM
Just use a long screwdriver and put a strong magnet on the shaft. That will keep the slotted screw on the blade. Brownell's magnetic screwdrivers accomplish the same thing.
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strat81
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Posted: 6/23/2009 12:19:52 PM
[Last Edit: 6/23/2009 12:20:04 PM by strat81]
***UPDATE***

I stopped by the hardware store last night. The only 1/4-28 screws they had were hex-head cap screws, so that's what I bought, including an extra long one. I also picked up a tap.

I planned on running the long screw through from the trigger area, but the lower wasn't threaded all the way through (it's a Spike's lower). So, I oiled up the tap and went in from the bottom. Cleaned everything up with some alcohol and they looked much better. I put some blue loctite on the screw and installed it.

Of course, the only hex drivers I have are short wrenches, so I had to use a Torx bit (which fit perfectly, FWIW). It went in fine.

You might want to tag this for the report in 6 months of "My grip fell off because if my lousy tap job!"

Many thanks to all who replied.
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USMC-Helo
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Posted: 6/23/2009 1:49:01 PM
Too bad no one can find a Torx Head Screw the right size and thread, I would think that would be the best of both worlds. Only down side is the ability to service in the field with minimum tools.