Ar-15 grip help SE PA? Builders help?

[orangehole]

So I bought a brand new S&W M&P Sport 15. I also bought a set of magpul furniture for the new AR. Everything went well (handguard grip, fore end grip, and stock) until I got to the magpul moe pistol grip. I removed the old oem factory grip with hex head screw and tried putting in the magpul grip and the magpul screw binds up. I tried different tricks I read about on thet net but I cant get the damm screw in. I am not sure if I stripped the threads on the lower because I cant get the original grip hex head screw back in. Did I just destroy a brand new AR? Any help is appreciated. Every video I watched on this made it look so easy. This is so frustrating!

[Bang]

Try putting just the screw back in, leaving the grip on the table? If a stripping has occurred, it will be the aluminum (lower), not the steel screw.

Look at the threads of the screw under magnification. You may see bits of aluminum clinging, a sure sign threads have been damaged.

Do not despair. Gauge the threads of the screw and "chase" the threads with the appropriate tap. It may straighten out the threads and become useable again. If that doesn't work, the threaded hole can be re-drilled and re-threaded the next size up. Tip: Sometimes changing from SAE to a metric size is a lesser jump in oversize replacement. Then just use a larger diameter screw. (You may have to drill out the MagPul grip to accommodate the larger screw).

[orangehole]

Thanks for the tips. I took a bunch of pics. see below.
http://s603.photobucket.com/user/auc...how/Flashlight

http://s603.photobucket.com/user/auc...how/Flashlight

The threads on the lower look a bit worn but not blown out bad. I am somewhat mechanically challenged so I wont be doing any re-drilling or re-threading as I dont even have the proper tools for that and god knows I will most likely end up destroying the lower.
I recall this similar problem happening to me when I build my first AR with a magpul grip and after a few tries, the screw caught the threads but this one is not budging. Both the magpul screw and original hex-head screw will initially turn in fine but then locks up after a little bit and I dont want to put so much torque into it that I cant get the screw out.

[Xringshooter]

Those first few threads need to be cleaned up. DO NOT try to do that with a screw, it needs a tap to do it correctly. If you are not up to it, take the lower off and take it to a gunsmith (or someone who is versed in using taps and dies). Take your original hex head screw and the new screw from the Magpul to compare the threads. The Magpul, IIRC, is 1/4-28. If the original is a different thread you should be able to use the original screw with the Magpul. You just may have gotten the Magpul screw started at the wrong angle and it messed up the first couple of threads. Cleaning them up with a tap should fix the problem.

[orangehole]

Yep I think that is what happened. I used the supplied magpul screw and must have gone in at a bad angle. I was real excited to get this new M&P sport for a killer deal but now I have an overpriced paperweight that is going to cost me more to fix. Thanks guys.

Any recommendations for a gunsmith in delco pa to do this job for me?

[aubie515]

I'm pretty sure I have a tap to clean those threads as I used to do it for my triggers.

You have to start the screw on an angle. I'm in Pottstown, if you want to borrow my tap.

[Xringshooter]

It doesn't necessarily have to be a gunsmith, although a gunsmith would probably have the correct tap as it is a bit odd sized being a 28 pitch (1/4-20 is the most common thread). If you're close to Aubie515 he will be able to help you. Will take about a minute to recut those first few threads.

[orangehole]

Update....Thanks for all the tips and help. I ordered a $3.99 1/4-28 tap from Amazon and ran it through. It cleaned up my threads and I was able to get the grip on. All is good now!

[Emptymag]