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1/25/2018 7:38:29 AM
Posted: 12/21/2005 5:08:18 PM EST
I'm not sure if this belongs here or in Build it Yourself. I decided on Troubleshooting because I am in trouble.

I finally bought a BUIS for my AR and I wanted to get a rough zero with the irons before I headed out to the range. I flipped up the BUIS to co-witness with the EOTech and dialed in my windage and then moved to the front sight. I can’t get the post to budge. The plunger is free and moves up and down easily but the post itself seems to be frozen. How frozen? I sheared the posts off of a front sight adjusting tool. I grabbed the post with locking pliers and tried to rotate it while depressing the plunger and, yup…you guessed it, I twisted the post and it sheared off leaving a little tapered high spot that I can’t grab with pliers. I also tried to rotate the base with a punch while depressing the plunger and I just cannot get it to turn in either direction. Should I try cutting a notch in it with a dremel and use a flat head screw driver to turn the post out? Should I file it flat and drill it? Should I kiss it with a MAPP torch before I try and rotate it again? I’m hoping someone’s run into this before and some sort of “approved” method exists. I really love my upper and I don’t want to bugger it up. I welcome your suggestions.


Link Posted: 12/21/2005 5:48:33 PM EST
Have you tried working some CLP in around the post? A couple of drops around the base of the post from the top, and a couple more through the hole in the Front Sight Base underneat the post might penetrate enought that you can start working it loose.
Link Posted: 12/21/2005 6:15:58 PM EST
Link Posted: 12/22/2005 2:33:42 AM EST
I'll try come CLP. The plunger moves so freely that I didn't think that the post would be frozen.

I think the barrel is a DPMS. I looked but I didn't see a set-screw. I'll check again.

Link Posted: 12/22/2005 5:54:35 AM EST
Link Posted: 12/24/2005 2:25:21 PM EST
I finally found time and removed the GG&G sling thing and inspected for a set screw and found none. I then sprayed the post with PB Blaster and let it set for about an hour. I then added some CLP and again put it down for an hour. I didn't want to take any chances so I heated the post with a MAPP torch until what was left of the post glowed red. I was then able to spin out the post using a sight tool. I don't know why it froze but I'm glad it's out without any filing or drilling I made sure there was clp on the threads before I installed a new post and was able to use my new BUIS to co-witness with the EOTech and zero the post. Now all I have to do is find some range time to make sure I'm good to go.

Thanks for the helpful suggestions.
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