Cant get AR15 FSB taper pin out (got 1 out, 1 stuck)

[Kharn]

I bought a slightly-used Colt HBAR barrel off the AR15.com 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

 

[Chris Rhines]

Freezer is a good idea.
Dousing the entire thing with penetrating oil may help.
Last resort is to break out the drill press.

- Chris

 

[dfariswheel]

These AR taper pins can be REAL tight.

You've got to get a good SOLID braced set-up so nothing can bounce,
and you need to use a good, heavy-duty starter pin punch. This is just a punch with a short 1/2" or so working length. Once the pin starts to move, switch to a full length punch.

If the pin doesn't start to move with a normal hammer and punch, BE CAREFUL.......If you continue to hammer on it, the entire ecposed section of the pin can expand, locking the pin in place immovably.

Try re-bracing the assembly, use a larger, (preferably no-bounce hammer) and a larger diameter starter punch to get it moving.

If it's already expanded and locked in place, drill the LEFT, small end of the pin, into the sight base slightly. Often this will remove the expanded portion, and the rest can be punched normally.

If this doesn't do it, you'll have to drill the rest of it.

 

[Kharn]

Well, I'm in a pickle now.

Taking a look at the barrel, the front sight base seems to be aligned properly with the gas port (I can thread a piece of solder through the front sight base and into the barrel with a little effort and work, I had moved the FSB but put it right back in place when I realized the gasport location), so the problem seems to be with the gas port not being in line with the pin on the barrel extension that goes into the slot in the upper.

I reinstalled the taper pin (and gave the stuck one a whack in case it had come loose) and let the whole assembly warm back up to room temperature so everything would be stuck back in place and then tried to rotate the barrel in the barrel extension, but only succeeded in shifting the front sight base on the barrel a little.

Any ideas?

Kharn

 

[curt]

FIrst of all STOP! I mean you've started banging on the FSB and torquing things around without knowing what you are doing. So my advice would be to stop and take it to a gunsmith.

What probably happened is that you've shifted the barrels index pin in the corresponding slot in the reciever, possibly by installing it with barrel blocks instead of receiver vise blocks.

I mean i hate to sound negative here but if your FSB was sitting at 1:00 when you were done installing then you haven't installed properly and now you're making things worse.

Take it to a smith.

 

[Wildalaska]

Any ideas?

Gunsmith time

WildfixingmistakesAlaska

 

[Kharn]

In my defense, I actually used the Bushmaster reciever block, BM heavy-duty barrel wrench and a torque wrench (and followed the US Army armorer's manual to the letter up until I tried to pop the FSB off), not the barrel blocks, to barrel the reciever.

Before I even spun the barrel nut onto the upper reciever it was obvious that the FSB was canted, but as my last rifle build (this was my first AR15 upper build) was an FAL, I thought it would work itself out when I torqued it down (as the FSB was under-timed).

Anyone know a decent AR15 smith that could fix this (re-pin the FSB and press off, align and press on the barrel extension would be the required actions, I think), and how much should I expect to pay?

Kharn

 

[curt]

Kurt's kustom in fl. is the guy i would use for any AR work, he has an excellant rep and does good work from what i hear.

http://www.kurtskustomfirearms.citymax.com/

FWIW i'm not sure that the extension will need to be done although if you're timing that badly its possible. It may be that a new index pin and some judicious peening could fix the problem. At any rate it sounds like the guy before you didn't know what he was doing so i'd get someone who knows ARs to check it out.

Good luck.

 

[Kharn]

Kurts Kustom said he'd take care of it for $45 plus shipping both ways (I showed him some pics of it, he said its probably just a loose/mis-aligned FSB, so I'm having him re-align the FSB, install over-size taper pins and barrel the upper; removing my inexperience from the equation). Hopefully I'll have it back before Christmas or New Years, parts go in the mail tomorrow.

Kharn

 

[Badger Arms]

For $45 bucks I'd just cut it off with a die grinder, buy a new sight tower, swivel rivet, and taper pins, and swap out the swivel and sight post parts from the old sight. But that's just me. Based on the preevious posts, I'd take it to pretty much any local smith. Sending it to KKF sounds fine, but you'd be wasting money on postage and wasting time. Reminds me, I have to send him my M-4gery upper for barrel retapering!

 

[Kharn]

There arent any local gunsmiths around here that I know and trust. Since I'm a college student (home on Thanksgiving break at the moment, heading back to school for three weeks tomorrow) and rarely have time to shoot, the extra turn-around time doesnt bother me.

Kharn

 

[444]

"Hopefully I'll have it back before Christmas or New Years, parts go in the mail tomorrow."

I hate to rain on your parade but that would be the second Christmas miricle. I sent them a 16" Bushmaster upper to have the barrel turned down to his lightweight configuration along with the installation of one of his muzzle brakes; it took over three months. I currently have a Bushmaster M4 upper there to have the Mini-Y-Comp muzzle brake removed and a new one installed: I had actually forgotten about it. It has been there for at least a couple months.

If you send the stuff now, you will be all set for your summer break.