I have a cerakoted Brownells BRN-16A1 lower. The front pivot pin is from a PSA lpk and it seems tight to move with the lower by itself, but not overly tight. I've tried to put 5 different uppers on and it either won't go in or it will barely go in then bind up. Rationale says the pivot pin is out of spec or the "ears" that hold it are out of alignment. I measured with calipers and everything checks out, so what gives? Takedown pin runs through with no issue. The PSA upper I tried I noticed had to be raised to engage, as in I could almost slip a piece of paper between top of magwell and bottom of ejection port. With measurements adding up I'm at a loss for what to attempt to fix. Best guess is takedown pin, but how do you find a smaller spec pin? Order 5 and return the largest 4?

Just so we are clear on components in case anyone is aware of a known issue:

Lower: Brownells BRN-16A1

Pivot pin: PSA

Uppers tested: Colt AF, Umbrella Corporation, Fulton C7, PSA, BCM

The coating inside the ears may be the cause of the problem with the pivot pin not matching up with the upper properly. When I have that happen, I will generally tip the upper forward and work the pin through the front pivot pin hole to see where the problem is.  You can also do the same thing with a  1/4" drill bit.  Because the drill bit it tapered on the end. I tap it through an ear and then wiggle it around to see if I can start it through the front pivot pin hole and then if I can I will lube the crap out of the pivot pin hole while working the upper up and down until it closes properly, then I tap the pin back and forth until it moves freely and the upper rotates easily on the pin.  Over the years I have had this happen on several different brand lowers and uppers it's a matter of machining tolerances between manufacturers.  
(EDIT) Another thing to look at is if the coating on the front of receiver between the ears is too thick to allow the uppers to rotate into place properly.  If you have been trying to fit uppers, you may see some rub marks in that area.  The easiest way to deal with that is to lube the area and work an upper up and down until it fits into place.  I wouldn't bother trying to remove any coating in that area.

I had to replace a front pin once that would binding going in because it was not straight. Just a bad pin and you could not see the bend in it but it was off. Starting out thinking it was the upper or lower but it was the pin.

JP rifles sells off size pins.

I've seen very stiff detent springs. You can try changing those out.

You can press the front of the upper and lower together and push the pin out.

Does the pivot pin go in with the rifle open?   If it only binds when closing and pushing in the takedown pin the problem may be your buffer tube.  You can't see it but if the buffer tube is turned in too much it will prevent the upper and lower from closing and seem like a pin issue.  Try backing the buffer tube out one turn while still capturing the buffer weight plunger.

Buffer tube isn't attached right now. Waiting on an A1 stock. I ordered a set of undersized pins from JP so see if that alleviates the issue. I can feed an exact sized wooden dowel through the other side just fine so hopefully the JP pins work.

Thanks for the input, fellas!



And no, the Law folder isn't staying on. I was just curious how it would look on an A1 back end. Not well, as it turns out

This is probably what it has to be. My calipers say that everything checks out and should fit fine. Hopefully the JP pins will just remedy the issue.

You don't have your buffer tube installed but you do have a folding attachment installed.  It will cause the same issue if it is in one too many turns.  You only need to capture the buffer weight plunger by the leading edge of the threads on your adapter.  Try backing it out one turn. Can't hurt to try.  Good luck.

If you look at the photo, the threads on the adapter are not a factor.

I agree with trying a different pivot pin.

New pins came in and it works perfectly, albeit with a slight wobble (from being intentionally undersized). So I did some more measurements with the old pin completely out of the upper, as well as  tried to insert the old pin into an upper by itself. Turns out the old pin wouldn't even enter the upper. Just barely oversized.

So I put another standard pin in the lower and *presto* we're in business. This was a good lesson in having parts on hand that you didn't think you would need until you run into an issue like this. However, I could have avoided purchasing the undersized pins altogether if I'd just tried another standard pin in the first place. What I get for assuming it was correctly sized and that I was measuring correctly.

So if I ever run into a problem like this again that really needs an over/undersized pivot pin, I already have the part for either issue.

Thanks for all the input, fellas!

No it turns out the original pivot pin I tried was just too large to enter the upper. My calipers couldn't even pick up the difference. I didn't realize it until I had the pin out and tried to insert it into the upper by itself. It fit the lower just fine.