Takedown pin not staying locked in... But locks out

Got a new lower (actually lowers) today. Assembled one with an Anderson lpk. Got the rear takedown pin in, and the damned thing doesn’t lock in the closed position. The spring is there, and the detent, and it locks in the out position, just not closed position (inward). Before anyone says the spring or detent were left out, that is not the issue.

Thinking either the recess for the pin isn’t deep enough for it to go all the way in, or the spring/detent hole may have been machined slightly off axis.

Downside is it is a NorGuard coated billet matched receiver set. If I decide to send it back, I will be waiting for at least a month till a new batch is out… AND I already have my ambi-catch, trigger, KNS pins, everything together. Was planning on finishing it up and going to see how it runs Sunday, or Monday.

So, without sharing the manufacturer for bashing, any suggestions? I am waiting on their solution, but thinking of what I can do.

Maybe slightly elongate the detent hole in the rear pin?

I have another lpk and a few extra rear pins. There is a possibility the pin was made wrong. Although when talking to the company looking for support, one of the few they tried did the same thing. Maybe the coating is slightly too thick.

Thanks for any input/suggestions.

Pull that pin out and inspect the slotted groove to make sure it was machined correctly. If its a billet lower it may be slightly thicker on the outer dimension, and not seating. If so, your options are as you mentioned, go through the hassel of machining that tolerance & recoat. Elongate the recess in the pin(what I’d do). Or try to exchange the lower.

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So, I got to dicking around with it. Tried several other pins, and one pin works fine in each. Took measurements and that one pin has the hole machined more away from the stop side/outer side.

Guess I am going to modify the pin holes.

The pins I have are from Anderson Arms. I think it is combination of pin tolerances vs thicker side area on the billet lowers.


I’ve had the same problem I just open the the deten/spring hole and that took care of it.

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