stuck pivot pin

[Disciple]

I got an AR upper and lower, and I ran into a problem trying to put them together.

The lower is an LMT Defender, and the upper is a Rainier Arms / Daniel Defense job.

The takedown pin dropped in just fine, but the pivot pin did not. I tried gently tapping it in with the plastic handle of a screwdriver, and now the pin is stuck just far enough in that I cannot separate the halves.

Honestly, I did not tap hard, and I am surprised it is stuck, seemingly quite firmly too. I am also surprised that there is a fit issue with what I believe(d) to be high quality parts.

No damage was visible to either part before I attempted assembly.

Where do I go from here? :confused:

[bluepythons]

First thing I would do is get some Kroil, it is a penetrating oil. Put some of that around the pin on both sides and let it work in. It really works very well and creeps in to very tight places making things easier to get out whether it be a pin, seized screw, etc. After you let that soak in for a while try using a derlin or plastic punch to punch out the pin lightly, with the Kroil it will probably take less effort. If that doesn't work move up to a pin punch. Make sure you support the tab with a plastic block or wood that the pin goes in and don't whack at it to hard. You can break off that tab as well as the "ear" for the trigger guard pin. Don't freak out about breaking something but don't take your big a$$ hammer and start hitting hard as you can. A block with a hole in it works best like the ones Brownell's sells. You can get the oil there as well.

Good luck, worst case you may have to buy a new pin but with patience you will probably be just fine.

Dave

[Disciple]

Dave, thanks for the instruction. This is all new to me so I appreciate knowing that the tab is vulnerable. Is the detent at risk as well?

I should be able to bump the pin back out as you describe, since again I did not tap very hard, but what happens after that? Am I ignorant to expect these two halves to fit together without fitting by a gunsmith?

[JStor]

Once you get it out, measure the pin with a caliper to see if it is out of spec or oversized. Measure the hole, too.

[Parabellum9x19mm]

+1 to bluepythons

the derlin punch is very useful. i think the only problem is that you're being too gentle. lube it up, get a plastic/derlin punch and non marring hammer and whack it in or out. supporting the tab underneath is a good idea if the fit is super tight.

brand new uppers and lowers can be very tight, it should loosen up after some use.

[Kaos]

Dave, thanks for the instruction. This is all new to me so I appreciate knowing that the tab is vulnerable. Is the detent at risk as well?

I should be able to bump the pin back out as you describe, since again I did not tap very hard, but what happens after that? Am I ignorant to expect these two halves to fit together without fitting by a gunsmith?

The detent is a $.75 part at best, I wouldn't put much worry there. Worry about the lower.

You could try getting a hold of another pin as the one you have may be out of spec, who is the MFG on the parts kit? As suggested, a micrometer (cheap one from any hardware store should do) can bu used to give is the diameter of the pivot pin itslef, and also of the hole in the lower, and the lug on the upper while you're at it.

[Disciple]

i think the only problem is that you're being too gentle. lube it up, get a plastic/derlin punch and non marring hammer and whack it in or out. supporting the tab underneath is a good idea if the fit is super tight.

brand new uppers and lowers can be very tight, it should loosen up after some use.

After tapping out the pin, which was easy, I inspected the area and alignment and it seemed good. I packed the area with grease and tapped back it, this time all the way. It's darn tight, but not tight enough to keep the pivot from pivoting, so I don't see it being a problem. I will have to be a little careful if I need to separate the receivers for some reason.


The detent is a $.75 part at best, I wouldn't put much worry there. Worry about the lower.
I should have said the detent channel in the receiver.


You could try getting a hold of another pin as the one you have may be out of spec, who is the MFG on the parts kit?

This is a factory LMT Defender 2000 lower half.

I do not have a micrometer, but this is motivation to get one, and I will be needing one anyway, sooner or later.

[bluepythons]

Sorry it took me a while to read your reply. Sounds like you got it out and like other said small parts are cheap, lowers are not. If you have to replace some small parts, no big deal, buy some spec quality parts and your good to go. Check the hole size, like others have said. Another thing to be aware of if you had your parts coated, duracoated, or painted, there may be excess build up in some spots. Buy some Kroil though it can be an armorer's best friend at times.

Dave