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Posted: 7/21/2008 7:37:45 AM EDT
I'm new to match rifles, but not new to AR's, and I'm building an A2 service rifle, so please be gentle. I'm trying to get started in service rifle, I know it's probably cheaper and easier to go with a RRA upper or something similar, but I enjoy building almost as much as I enjoy shooting. So, here's the situation. I have a Colt Marietta (CM) upper. The sights are marked 8/3, and the windage knob has 97 clicks from stop to stop. Each click is about .00686". I'm not sure, but I think that equates to about 1.3 MOA per click, so I guess I need to replace this sight? If so, what should I replace it with? Should it be pinned? If so, what is the procedure? I'm proficient with a vertical mill, so drilling would not be a problem. Thanks.
Link Posted: 7/21/2008 10:20:19 AM EDT
[Last Edit: 7/21/2008 10:24:29 AM EDT by wrangler]

I like building them too! I do most of the club members plus my own.

I have installed the RRA NM rear sights on many uppers. On a RRA upper they line up really good with the front sight and don't need pinned.

Another alternative to pinning is to install another spring and ball detent on the opposite side. Then you will have two spring loaded ball detents that will line you up with the front. Since you are familiar with a mill, you should have no problem drilling the added hole in the rear sight base.

You can also align the rear sight to the front with JB Weld (quick) by putting a feeler gage between the sights base and the carry handle. About .011" is the average build up with the JB. Measure your rear bases width and add the feeler gage thickness. Set your dial calibers to this measurement and file down the JB Weld.
Install and your set for life for about 25 cents!

The RRA sight are available from Steve at ADCO. I recommend you get 1/4 minute elevation and windage with .040" hooded rear aperture.


Dave McGrath

Link Posted: 7/21/2008 10:20:32 AM EDT
I have upgraded a few Colts as well. You definitely need to do an upgrade. However you do it, go with 1/4 min Windage and Elevation. WOA is where I would go for either parts or to have them install their pinned 1/4 x 1/4 hooded sight. You can always buy their parts, install and use them and get them pinned later or never. Their sight installed and pinned is like $280 shipped, plus you send them your upper. Call them and discuss options. You can save a bit by just upgrading your current sight with the minimum of parts. WOA (309) 376-2288
Link Posted: 7/21/2008 9:57:17 PM EDT
Thanks for the detailed replies. I decided to go with the RRA 1/4 X 1/4 hooded .40 sight from ADCO, primarily due to the lower price I got from Steve. I also think I'm going to drill it for another ball detent, that seems like an elegant solution. I appreciate the advice.

Link Posted: 7/22/2008 9:41:19 AM EDT
If you go with the JB, just build it up on the lower right.

The double ball detent, I believe was Derrick Martin's solution to canted rear sight bases back in the mid 90's. A little tricky to install but a dab of grease on the detents hold them in places until you get the elevation knob turning to lower the base.

Dave McGrath
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