I bought a slightly-used Colt HBAR barrel off the EE a few weeks ago and finally got around to installing it on my reciever.  Noticing the front sight base was canted to about 1:00 (when viewed from the rear, previous owner had it on an upper with a float tube and there was evidence the pins had previously been removed and reinstalled) so I decided to knock out the taper pins and correct that.

The rear taper pin popped out after about 5 whacks with hammer and punch, but the front pin is absolutely refusing to move.  I mic'ed the pin and I am hitting it from the correct side (and in the same direction as I hit the rear pin), but I've been going at it for about an hour now and it has refused to move no matter what I do.

I just threw the barrel and upper into the deep freezer, maybe that will help after a few hours.

Any hints or suggestions?

Kharn

Would you enlighten us on how you plan to realign the barrel gas port and the front sight gas port after you have spun the front sight tower on the barrel?  

Just put the taper pin back in the front sight tower and lets start over on correcting the problem.

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To correct your problem, you need to rotate/slip the entire barrel in the upper barrel socket to correct.  You can do this by reinstalling the barrel and prevent the barrel from slipping out of index as you tighten the barrel nut.


Or, hold onto just the receiver, then strike the front sight tower just above the barrel with a leather mallet to slip the entire barrel (not just the sight tower) in the upper barrel socket to get the front sight to the correct index.

Alright, got the rear pin back in.  Now I guess I have to wait for the whole thing to warm back up to room temperature before I go whacking at it with a hammer.  

The barrel was already out of index when I got it (it was obvious as soon as I got the pin lined up with the slot in the upper reciever), but I didnt think anything of it at the time (as my last build was a FAL and I was thinking it'd index correctly (and the gas port would be big enough that being slightly out of line wouldnt be a problem, never realized how small an AR's gasport was until I just looked) when I finished torquing, but obviously that wasnt the case).

Kharn

Ugh, looks like its now a job for a good AR15 smith.  The taper pins no longer hold the FSB on steadily (I can rotate it with a strong push), and whacking the FSB to turn the barrel is out of the question.

Any suggestions on which smith to use, I think I need the extension realigned and new taper pins installed?

Kharn

It's cheaper to just buy a new barrel at $129, then for a smith to re-work the barrel.

I've contacted KKF, he thinks its just an FSB mis-alignment (from the pictures I sent him), so he's going to re-align it and barrel the upper for me, for a lot less than a new barrel.

Kharn