Pivot pin wouldn't go through, easily...

[Madhouse]

So, this was interesting.  After I assembled the parts on my POF lower last night, I was mating it to the POF upper.  I put the lower in place and the pivot pin would not enter the lug on the upper.  It was aligned just right, it just wouldn't go in.  So I spun the lower around and pushed the pivot pin in from the reverse side, and it went in, but stopped just shy of exiting the right side.  I started thinking there was a burr or something, but couldn't find anything, and the calipers showed the right size.

Since I'm in the pipeline industry and we live by the code "Hammer to fit and paint to match!", I put some CLP on the pivot pin and in the lug hole, pushed the pin in reversed again, and tapped it through with a small rubber hammer.  It went, reluctantly, so I tapped it back out, then repeated the process and it got progressively easier, until I was able to do it by hand.  I put the lower on properly and am able to push the pivot pin in and out with a fingertip now.  It took a little finish off the pivot pin, I guess the hole was just a FRCH too tight..??

<dontknow>

[TacBlade]

On my build, the detent pin was so sharp, it was holding the pivot pin very tight. After tapping it in a couple times, the tip rounded off a little and its about right.

[survivalshop]

Probably just extra coating from the receiver finish application .