AR technical questions

[ralfabco]

I want to buy a Giesselle trigger for my AR. How do I know, if I have a small or large pin ?




In addition, I have the Post 1994 Colt Match Target lower. I guess, it does not even mount the (milspec) Colt uppers ? I am sure these have a sear block.

Is a universal pin available, that mounts the front of the receiver, to the front of the upper ? Again, you have different holes.

Thanks in advance.

 

[Captain Kirk]

Re: AR technical questions

Colt runs the "large pin" .169 and everyone else runs .154. For Some of the older Colts, you need a offset front takedown pin.

 

[salmonaxe]

Re: AR technical questions

You can also get a flattop upper with the big front hole.

https://danieldefense.com/big-hole-upper-receiver-assembly-b.html

And you can get rid of the screw in the front and use a detent style from KNS. (only useful when used in conjunction with the bighole uppers)

http://www.knsprecisioninc.com/gun-parts...in-315-dia.html

 

[ralfabco]

Re: AR technical questions

It is not an early Colt AR-15 lower.


It is a Colt Match Target Post 1994 lower.

 

[salmonaxe]

Re: AR technical questions

A buddy of mine has a post 1994 ban era Colt match target. It has large trigger pin holes, the sear block and the large front takedown hole that uses the pin that is captured by a screw. Sounds next to identical to yours. His has a 20" Hbar with a bare muzzle.

He got an upper just like the one I linked and we swapped everything over so he could run a scope. I know he was looking at getting a Giesselle trigger for it.

I think the term "old" is relative. There are SP1's that have small trigger pins. There are new 6920's that have small takedown and small trigger pins. And a slew of other configurations. I have buddies who are really well versed in the nuances, but I really didn't care much about that crap.

Just take a pair of calipers to your pins and use kirks measurements.

 

[tylerw02]

Re: AR technical questions

You'll have to measure to be sure. Sometime in 2008-2009, Colt went back to .154" trigger pins on everything.