Re: RMR as primary AR sight???
I haven't tried it either personally, but I suppose it would work fine. The biggest problem I see is speed of target acquisition and the FOV. See, I have a 1x24 RX01 and compared to the EoTech 512 I have, it is much, much slower. The dot is also quite a bit dimmer, so if you get an RMR you may want to consider the one that has battery backup. Also consider the new EoTech's are getting smaller by the day, the price is similar, and the EoTech supports a magnifier if you choose, not to mention various reticle options.
I actually didn't like the EoTech when it came out, I thought it was cheap and not effective. Boy was I wrong. It is now my favorite, my preferred reflex sight by leaps and bounds. Only wish it was tri-powered like Trijicon's "Tri-Power", as I do like no battery options when applicable, but it is nice to always have a sight that works to some degree or another regardless of lighting. The biggest problem with tritium reflex sights that also employ fiber optics is that they compensate for the lighting in which they are located. So if you are shooting from a dark room into a bright, sunny outside, the tritium dot can easily get lost and require "searching". Not cool. When lighting is same on target as it is for the shooter (like at your range) this isn't a problem.
Now I plan on putting canted reflex sights on some of my scopes and/or scoped rifles, and the RMR is a consideration as is the Aimpoint Micro for at least one. I've heard a lot of good about the Micro too, to tell you the truth, and not too much about the RMR.
Also, fwiw, I've seen a LOT more Micro's being used as primary sights on rifles vs. RMR's, usually CQB weapons but occasionally the 5.56 rifles, and considering the price is similar, I'd probably go with the Micro if it was going to be the primary sight.
I should also mention that the RX01 is quite a bit less accurate than is the EoTech. I get, oh, about quarter size groups at 100 using the EoTech and a decent non-FF 14.5 LMT M4, while the RX01 opens up a good deal more. This could be in part to the ARMS mount I'm using or it could be the fact that the entire base adjusts and not the reticle itself. I don't think this is an issue with the RMR but I don't own one so I don't know for sure.
Simply put, I personally wouldn't use the RMR as a primary sight if the EoTech will fit the bill, and on top of that, many flip up sights will co-witness absolutely with the EoTEch and I'd highly recommend using some kind of backup irons, co-witness or not, and though I prefer the KAC 600m flips, a lot of folks swear by those plastic Magpul backups. Considering they seldom get used after sighting in, they may be the better choice. I don't know, like I said, I mostly use KAC gear when I can. My M4 is basically the same build I had in the army only with minor parts changes (like a Geissele trigger instead of burst obviously and I have an AAC Brakeout for a suppressor). When I use the EoTech, either the KAC 600m flips or the ARMS flip (L40?) will line up perfectly with the fixed front sight and the EoTech basically halos the irons and the dot sits right on top of the post. Couldn't ask for better co-witness if you ask me. The RX01 will do the same, but with a much, much smaller window to look through, it is much slower and in certain lighting you have to "search" for the dot. Not cool at all. So I use the RX01 for a primary on a Beowulf, which is a 200m max weapon and that seems to be pretty accurate on the Beo. Don't ask me why.
I do plan on using a canted reflex on a couple of scoped rifles in the future, again I haven't decided on the RMR or the Micro, but most folks seem to go for the Micro from my "research". I'll still keep the iron backups as I see the canted reflex on a scoped rifle as more of a luxury really.
But to each his own, I just feel the larger window of the EoTech is just superb compared to others. The Aimpoint red dots, the M68's and similar, they co-witness too but without the larger window and the 65MOA ring around the 1MOA dot is STILL faster, at least for me. But those Aimpoint M68's are tough as hell, I saw one get hit so hard it sheared the military rail grabber mount clean in half, but the damn M68 was totally unharmed, though it was what got hit!
Now on my ACOG equipped M4, I do plan on mounting SOME kind of reflex on top of it as those ridiculous built in irons are completely useless for up close, but considering I would seldom use it, I'll probably go with a J-Point and a Larue mount with wings so as to protect it some.
I'd maybe think of putting one of those small RMR's or similar very small dots on one of my pistols, maybe a G17L if I can score another new one later, or if we could have SBR's or say SBR PDW rifles in my area that were small and concealable, I would maybe consider one then, but just not for my M4 carbine or anything bigger.
Sorry so long winded, I just hope the comparisons helped.
