This may be a stupid question but I cannot figure out what type of Colt Upper and lower I have.  I have looked at this site, http://www.biggerhammer.net/ar15/uppers/ which helped alot.  However, the pivot pin is not the standard type pin that you would find on another rifle like a Rock River, Bushmaster, etc.  It has the screw pivot pin.  Does the screw pivot pin mean that it is a large hole upper?  I believe that it is manufactured in 1998, which according to the site is past the time that they were making large hole uppers.

I know that I could remove the upper and measure it myself, but I am trying to order a drop-in trigger and I noticed that there are different triggers for small and large (colt) receivers.  There is also a chance that I am misunderstanding what that means and that all colt receivers require this large size colt  trigger.

My AR-15 is actually in a different city at the moment.  I would like to be able to have the drop-in trigger waiting for me when I return from vacation.

Could someone please help me?  I just want to make sure that I don't purchase the wrong thing.

Thanks.

EDIT: I don't know if this helps, but the rifle is a Colt Match Target Competition HBAR.

Quoted: This may be a stupid question but I cannot figure out what type of Colt Upper and lower I have.  I have looked at this site, http://www.biggerhammer.net/ar15/uppers/ which helped alot.  However, the pivot pin is not the standard type pin that you would find on another rifle like a Rock River, Bushmaster, etc.  It has the screw pivot pin.  Does the screw pivot pin mean that it is a large hole upper?  I believe that it is manufactured in 1998, which according to the site is past the time that they were making large hole uppers. I know that I could remove the upper and measure it myself, but I am trying to order a drop-in trigger and I noticed that there are different triggers for small and large (colt) receivers.  There is also a chance that I am misunderstanding what that means and that all colt receivers require this large size colt  trigger. My AR-15 is actually in a different city at the moment.  I would like to be able to have the drop-in trigger waiting for me when I return from vacation. Could someone please help me?  I just want to make sure that I don't purchase the wrong thing. Thanks.

I'm pretty sure, from what you said about manufacture date it's a small hole.

civprod,

On both large and small hole pivot pin Colt uppers, they both come with screw pivot pins.

The difference is the diameter of the head of the screw, large head will have a large .315 dia. pivot pin and small head will have the small .250 dia. pivot pin.

From the date you stated, you have a very high chance it's a small pivot hole.

Most A2 and on lowers have the large .170 dia. hammer and trigger pins.

There are only a very few modern lowers that have the rare small .155 dia. FCG pins.

I have a 6721 Tactical Carbine and a Match Target HBAR models.

also, if you don't like colt's 2 screw system to their front pin (I really don't) Brownells'.com sells a replacement pushbutton front pin, that comes out a lot easier.

-mark

The large pivot Colts have a screw head on BOTH sides, while the small pivot Colts have a SINGLE screw head (which is on the left side).

Generally, if it has a small pivot, it will have the large trigger pins and if it has a large pivot, it will have small trigger pins.

From your description, it's probably a safe bet to assume that you have the large (.170") firecontrol pins.