Originally Posted by Aksarben

It is a polymer lower receiver, and as such if the holes drilled for the pins for the trigger and hammer are a bit out of spec, say larger, then you have issues with the hammer and sear engagement. Pin walking will cause wear on polymer a bit faster than on aluminum. I bought Colt 901 pins which are 1.00" long and not 0.900" long to better fit my 15-22 Performance Center rifle. They came from Brownell's just the other day. I drove both of them in, using the existing pins as "slave pins" and the length made it more flush HOWEVER, the pin for the trigger assembly was small enough to make wiggle in the hole that it resided in. Measured it after taking it out and it was 0.153. The pin I had originally, a S&W pin was 0.155 an extra 2 thousandth larger in diameter.

You can buy non walking pin sets, but what I did was get out the J-B Weld and plaster both holes and "PUSHED" the material down inside next to the pins. It set up and it is a lot more solid now.

Preferably I would have liked to cherry pick a bunch of pins and find 2 that were 0.157" dia and use those. It would have been a very tight fit, but I believe the polymer would give enough for the pins to pass through and they would be very secure then.

My theory is that the lowers are drilled too big and there is enough slop and clearance that some rifles will be out of tolerance for sear and hammer meeting in a safe and functional manner. Best advice I could give is to check over the holes/pin for good fit and don't oil them. If your new rifle shows too much play, I'd put in bigger pins, OR you can stake them with a hot small nail that will move the polymer material closer to the pins, and prevent rotation.