I could use some advice. I suspect the front pivot pin capture hole was made over-deep, because the detent pin was a standard, double-sided type, but that sucker is now stuck shut, and I can't put my upper and lower together!

I already did a search through the site and google, and read some suggestions for others with a similar problem. I've tried to use dental tools, both through the pivot pin slot, and through the spring weep hole in the receiver (to take some pressure off the detent pin), but had no luck with either approach. Dental tools were the only things I had with the size and reach to try to influence the detent pin.

I think my next option is to use a tiny drill bit to chew up the detent pin spring a little at a time (through the weep hole), and then see if I can get the detent to drop, so I can finally move the pivot pin.

Has anyone used another, non-destructive method for this problem?

I am mildly peeved at having to spend several dollars just for a tiny spring and pin, which should be made to a standard.

ETA: sorry, wrong terminology, I meant front pivot pin

Try hitting it out with a hard rubber mallet? Every time I build a lower I tap both take down pins back and forth a few times to kinda break them in a little. Yours might be a little tighter but maybe worth a try

I agree with trying the rubber mallet before trying to drill out the detent spring through the weep hole.

Remember that the rear pin is the takedown pin, the front one is the pivot pin.

I have a stag upper that I used for a build. It was going to mate with a PSA lower in a 22lr SBR build. I sweat the PSA was out of spec, or the rear takedown pin lug in the upper was too long. I could get the pins in, but dammit if it was super hard to get them to slide out. I mean I would have to basically use a punch to knock it out. It was so aggravating. I eventually went with an Anderson upper, and it worked. So I attribute this to tolerance stacking. I'm wondering if you may have a similar issue, where the holes just don't line up right.

Dang, you are right, let me edit the title and body, I was referring to the front pivot pin. Long day.

I tried a mag block, punch, and hammer as well, assuming it would round-over the detent pin, and it didn't budge. I was afraid to knock off the front pivot holes at the rate I was going!

Squirt some Kroil, PB Blaster, Ballistol, or some other penetrant/lube around the pivot pin on the detent side just to make sure the detent is not stuck. If you are whacking it with a hammer it should move. The pivot pin went through the hole at least once. Something changed in the interim.

I polish off the ends of the detents before assembly to avoid this problem. Also helps if you put a little grease in the track on the pin.

Try some CLP.  I use that in several areas for my lower builds.

Don't worry, pins will not walk out when using CLP for the install.

I'll echo the lube recommendations. If you have a needle applicator (or a spray can with a straw), point the receiver down, and fill the spring channel with some form of lube through that weep hole you were planning to stick the drill bit into. Once you see the fluid wetting around the pivot pin, you know it's gotten through to the detent.

You may have to drill through the pivot pin and remove the detent and spring. You will need to replace the pin, but trying to get the pin to move by hammering coulddamage your lower.

You may be able to get in between the pin and lower with an xacto blade and walk the detent pin back. If not i would suggest a drill and a dremel and drill out the pivot pin until the detent pin comes out.

Yaaa your right I tend to refer to both the take down pin and pivot pin simply as "take down pins"

The pivot pin should have a small hole drilled through it where the detent pin seats when the pivot pin is opened.  Insert a small punch or drill bit into that hole and push the detent pin back into the receiver.  Rotate the pivot pin 90 degrees and then pull it free of the receiver.  Be sure and catch the detent pin and spring as they WILL be ejected from the receiver when you remove the pivot pin.

Try rounding off the sharp point on the detent pin with a small file then reinsert everything back into the receiver.  The pivot pin should now release from the locked position easier.

That would work for a pivot pin in the open position...this one is closed. When I did the install, I had assumed working it open/closed a few times would be enough to "round over" the tip of the detent pin, but that has not worked out.

Still haven't gotten it?

Dremel through the pivot pin, just before you cut through, aim carefully @ the target & you should it it w/ the damn detent.  If you ever find it, throw away the damn thing, and put a new detent & pivot pin in.

Yeah sorry for the long delay, haven't been able to work on it. Based on my experiences with the dental tools...I think I am going to have to dremel through. I may contact Anderson for a replacement pin. They have been responsive before, so I am hopeful.

Where in Georgia are you located?
I've got plenty of the parts you need and a large selection of tools.
PM me if I can be of help, I'm 10 minutes south of Macon.

Appreciate the offer but I am well outside of convenient range to Macon.

Hit it harder with a bigger hammer.  I have 2 new builds that are both impossible to remove pivot pin without hammer and punch.  They loosen up a little more each time I remove them.  A hundred more cycles and they should be finger tight.   try removing pin with the upper in different positions of open.

Tungsten disulfide is the most lubricious material on earth, more than any CLP, oil, or lube.

It's a dry lubricant. Use that. It will come free.

molybdenum disulfide works pretty well also. I picked up a big 'ol bottle of dow moly-z a while back and it has worked quite well on problematic firearms.

I may have to look into the tungsten disulfide though........