I'm trying to find replacement pins for an AR-180B lower that are longer than normal. I've considered have some made up but one of the fine folks who reads my blog suggested extended length pins like those used on a S & W 15-22 or a Colt 901. I also see that Mag Tactical lowers use longer than normal pins as well. I can't find lengths for these pins published anywhere so I am hoping someone here might own said guns and would be able to measure them.


I hope if we find something this post might help someone else down the road.


What I know


Standard length AR-15/M-16 .900"


AR180B length 1.125"

Colt 901 .995" (Thanks tomcatt51)

Mag Tactical ???

15-22 .900
If all else fails just make your own. I made some 1.125 out of 5/32 drill bits by cutting them to length and adding the required grooves with a dremmel in maybe 15min.

__________________
15-22 bullpup, "X-terminator"

You probably want: https://geissele.com/large-pin-colt-...mmer-pins.html
They're mis-labeled as "large pin". They are 901 Colt pins which are small diameter but longer for full engagement in the 901s' thicker walls. I have them in my S&W 15-22 which has a std size well but thicker walls like a 901.

How can the .900 measurement for the 15-22 be correct if .900 is standard AR length and the Colt 901 pin and 15-22 pin are longer. Tomcat, can you measure your Geissele pin for us?

Thanks,
Y2

Because the 15-22 pins are std AR-15 length (not Colt 901 length) and too short for the wall thickness of the 15-22 lower. They sit recessed, not flush with the exterior. S&W low balled this...

The Geissele pins seem to be right at .995".

Thanks for that. Any extra length up to the 1.125" of the AR-180B would help with the safety factor.

Just out of curiosity, do the 901 pins stick out past the sides of the lower receiver on the 15-22?

Barely. The lower measures ~.990" where the pin holes are so the Geissele pins are about perfect.

Thanks for your help gents.

I ordered a set of Geissele 901 pins and I think they are going to do the trick.

AR 15 pin on top
Colt 901 Pin in the middle
Original AR180B pin on the bottom



Original pins in the Nodak NDS-18S lower



Colt 901 pins in the Nodak lower.



According to my measurements the 901 pins have .150" of engagement per side as opposed to .100" when using the AR15 pins.

I feel these are safe to use in the billet aluminum Nodak lowers. I would not use them in an original polymer 180B lower.

You guys rock!