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.

Thanks,

Hanz

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.

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.

Thanks.

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.