From prior military service and personally owning an ACOG with an RMR piggy back, I feel I can give you some insight on the ACOG set up.
First of all the eye relief for the ACOG is @$$$$$$$$$!!! Especially when I went it was mounted on an M16 in front of a rear iron sight and stuck with a fixed length of pull because of the A2 stock. Could NEVER square off perfectly with the rifle while getting a good picture with no tube shadow. On the plus side because of the horrible eye relief you do get an extremely generous field of view. Alot more than most LPVOs.
Solution: Mount your rear iron (if you have BUIS) in front of the optic and move that sucker back to the last notch it can hang onto made all the difference. I did get my booty chewed out by Staff NCOs for being "different" but I didn't give a 2 sugars because it was my score and qualification I was going for.
Amazing how back then not knowing anything about "returning to zero," everyday after practice day and qualification day I would return my rear irons to the back of my ACOG and scooted my optic back up when going back to the squad bay to avoid an ass chewing lol. Then when getting ready on the line I would swap them back to my desired placement. This was with the thumb screw mount too haha. I did have a paint marker line where my zeroing torque was though so maybe that made all the difference. Never dropped "expert" on the known distance qual. When I made NCO I no longer cared and kept them the way I shot it. HOLY CRAP I digress haha. Flashbacks.
A very strong positive. The glass is stupid clear. I thought I had pretty decent eyesight but the ACOG prism black magic whatever Trijicon uses sharpens every detail of the picture the objective is looking at. Its almost like putting on a perfect pair of prescription glasses. The BDC is pretty much spot on minute of man as long as you're using the corresponding barrel length and bullet weight that the BDC is calibrated for. I've only shot out to 300 meters with my personal ACOG, but during qualifications in the service the 500 meter hash mark did put the 5.56 bullet in the black as long as your wind holds were good.
The optic body is very durable and extremely light. We were never nice to ACOG. They would rattle around in armored humvees, constantly fall over from being stacked poorly in the field, brushed, rubbed, chaffed, banged against hard objects in MOUT training. If I didn't appreciate the durability of the optic back then. I certainly do now.
I would consider this because of the horrible eye relief is. What caliber are you planning to shoot this out of? The 20" M16 shot extremely smooth and never got bit by the eyepiece. When I was issued and M4 though, in weird and crouching positions, the little bit extra kick from the carbine gas system (didn't know that was the reason why back then) was just enough to start having the eye piece jab me on the eye brow when I couldn't get the most solid of cheek welds. I don't even want to imagine having that short of an eye relief on a larger caliber and having the eye piece hitting you in the face.
My personally owned ACOG is mounted on top of a mid length gas AR and man, I do appreciate how well tuned civilian ARs can be. Never got scope bite from my AR.
The fiber optic can be overwhelming if you are directly under the sun. The bloom and glare on the cheveron from sun directly hitting your fiber optic strand makes it almost impossible to use your 100-300 meter points of aim.
Solution: electrical taping about 3/4 of the fiber optic helped for my eyes, make the cheveron crisp again. Actually for me, shooting the ACOG at KHSC in the shade with the no tape covering the fiber optic, and my target directly under the sunlight was the perfect amount of contrast and brightness for me. But do be aware if you do shoot under direct sunlight, you might have to manage how much light your optic is absorbing.
As for the tritium, you can see it in pretty well under no light, but I wish it was just a bit brighter. It is decently enough lit to pick up in low light. I would be comfortable taking 100 yard shots at night with some ambient light and the tritium lit cheveron.
The RMR mounted on the ACOG is nifty. I've come to really like it. As long as you're ok with going from a cheek weld to a chin weld I think you would like the rapid transition of magnification range. The height over bore will take some getting used to also I you plan on shooting 25m and in. I'm even thinking of switching the RMR to the Holosun 508t for the solar capability.
My apologies about the rambling, run on sentences and dis organized information haha. I'm probably not doing the ACOG any justice describing it to you, I've just spent so much time with it I pretty much know all the great things about it but even more so the small nuances that I have to work around to make it fit my preferences. Hopefully this helped you somewhat make a good choice haha.
