Hole and pin specs

[fbuccino]

I'm assembling my lower and the Trigger detent pin and hammer pin are really tight. Does anyone know what the specs on both items should be? Currently the hole is about .1555 and the pin is at .1565. Is it meant to be a press fit? Or is a little sand paper in order?
Thanks!

[m16]

No, it is not a press fit.

The pins should be smaller than the holes.

Did you buy oversize pins on accident?

There are a couple of companies that make 0.156" pins.

[fbuccino]

I bought a Rock River Lower parts kit and it came with the pins.

[m16]

RRA is one of the companies I was referring to.

They may have packaged the wrong pins in your kit, the pins should measure 0.154"

[fbuccino]

I bought two kits and all four pins measure the same. They also fit the trigger and hammer nicely. I read somebody offers an oversized pin, but it was a lot bigger.

[Drew Eckhardt]

I'm assembling my lower and the Trigger detent pin and hammer pin are really tight. Does anyone know what the specs on both items should be? Currently the hole is about .1555 and the pin is at .1565. Is it meant to be a press fit? Or is a little sand paper in order?
Thanks!

The receiver hole is not too small. That hole should measure 1.560 + .0015" before anodizing and is required to pass a .1560" gage block through both sides at the same time. Part of the anodized layer is beneath the original surface, part is growth so the hole will be smaller.

The pin is too big - .154" is normal. I don't know what the tolerance is.

[M1NM]

If I remember the oversize pins are for Colt and they are a lot bigger. If your pins are fitting the trigger/hammer well I'd lean toward cleaning out the holes in the frame rather than sanding on the pins.

[Drew Eckhardt]

If I remember the oversize pins are for Colt and they are a lot bigger. If your pins are fitting the trigger/hammer well I'd lean toward cleaning out the holes in the frame rather than sanding on the pins.

Colt pins (to preclude use of automatic fire control parts) were .169".

A .156" pin is an over-sized standard pin. Current production Colts have .154" pins.

[fbuccino]

As it turns out Rock Rivers pins run .1555 as they are assuming you are replacing worn out .154s or something. From some hunting around it appears they can be tapped into place using a soft mallet. A video I saw also suggested using the smooth end of a drill to line up the trigger and hammer from the opposite side before tapping the pin through.
One other tip I picked up was to cover the lower with masking tape then put a heavier tape on top of that to save the finish incase of a slip.
Thanks for the help.

[m16]

Correct, RRA and JP Enterprises offer pins that are slightly oversize.

If it were me I would order a set of standard pins, they are cheap.

[fbuccino]

I would, but then it makes the trigger sloppy.

[fbuccino]

After a little oil on the pins and a little tap here and there it worked like a champ. The trigger is nice and tight.