All this to move a sight mount one slot further to the rear.
I put away some of my toys to embark on other projects, and with Spring the ARs returned.
First off, no one in their right mind would do this, so I consider this to be a monument to my pigheadedness. Second, the TA50 ACOG version is not particularly popular, so why bother? Third, there are certain “behind the lines,” “AW ban,” legal considerations that impeded me.
What I wanted was a 3x-ish sight, compact, low weight, suitable for CQB-type exercises, and as low as possible above the bore. Yeah, I know a lot of people love the TA33s, but I owned one for several years and never really liked it (spent a more time hunting for that little chevron and the proper hold-over mark than I care to admit). I sometimes like the big reticules, like this:
I wanted to mount that sucker low, which meant using an American Defense mount. Since it is QD, it solves the “how to get it off without a tool problem.” The only mount lower from my investigations is the original Trijicon mount for the 3.5x or 4x scopes.
Since I was dealing with a fixed stock (“AW ban” state), I elected to go A1 length; anything shorter would be less stable for a rifle with a sight that could go to 300+ meters. In order to get the sight as far back as possible – to get a decent field of view with the horrible 1.4” eye relief available – and still have room for a BUIS (absolute requirement) I had to chop the AD mount and find a BUIS that could be chopped appropriately as well. Or, I could chop the bottom of the ACOG (no way!). Otherwise, I would have to have a QD mountable fixed sight, like the LaRue, and that would mean fumbling around with sights if the ACOG crapped out (not likely, but …) Of course, I could raise the optical sight by 0.5” with a $15 riser. But no. See what I mean about pigheaded?
BUIS? Many designs just don’t accommodate chopping well. Magpul’s MBUS will not accommodate chopping at all. GG&G requires removal of a lot of material. The best options I could find were the Troy BUIS, the DPMS Mangonel, and the Brownells BUIS. Removing material from a Troy seemed like a waste and the mangonel seemed overpriced and overlong. I went with the Brownells, and it looks like this:
Very basic BUIS, one aperture, held up by a fairly good detent. It’s a BUIS.
Chopped the AD mount with my handy milling machine. Oh, wait, I don’t have one. I guess Mr. Dremel did his duty. Too bad I had to lose the flag.
Of course, the bottom of the ACOG sticks out and I must create a shelf in the front of the BUIS to accommodate the excess. (I am not chopping a $900 optical sight to accommodate a $65 iron sight.) It’s pretty messy, but will not show. Where’s the grill paint?
I did this freehand, and even with the surrounding area masked off, it slipped a few times and the bit went straight through the duct tape.
I had to make sure that there was sufficient clearance on the sides of the shelf to allow the ACOG with mount to be “rocked on” from the side. After measuring about 47 times, I determined that the best way to do this was to mount the ACOG where I wanted it and, as I removed material from the BUIS, to occasionally slide the BUIS on the rail up to the limits imposed by the ACOG and mount. If I was able to push the BUIS beyond the point where I needed the locking bar to fit into the appropriate rail slot, then I was almost home. Just cleanup left.
Showing the lineup (where the sight would have been positioned prior to the work):
Now together with the rear of the ACOG in the notch:
Like I wrote, all this to move a sight mount one slot further to the rear.
My thanks to my constant supporter and companion, Mr. Bones.
