Gents,
I am curious about which BUIS system out there best co-witnesses with an Aimpoint Comp M4. I want to go with the Magpul system (try to save money when I can), but I am considering other options to. Thanks for any input.
-Dan
What exactly do you mean, “best cowitness”? Do you want lower 1/3 cowitness or absolute cowitness? What mount is the CompM4 in? What is your budget?
Absolute… planned on using the mount provided. I was hoping for opinions that were not budget limited.
I prefer ADM and LaRue mounts to the stock Aimpoint mounts, but that’s just me.
The best BUIS out there IMO is the Troy. Do you have a front sight base? You did say “system” so I assume you meant front and rear? And what do you mean by best? Blocks the least amount of view?
Maybe I’m misunderstanding you somehow, but usually your sights are all the same height and you choose your sight’s mount for desired co-witness.
They will all co-witness the same. Just make sure to buy an absolute co-witness mount for your optic.
I maybe missing something here about the question “it is 0200 here and I can’t find any bad guys”. You’re not going to get really any difference in a sight picture with whatever buis you go with. They will all co witness the same. You can get into fixed or folding and which sight is better made so on so on and so on or like 87gn said you can get into lower 1/3.
Ok, guess I didn’t go into detail. I don’t want to shell out the $ for a mount, do any BUIS cowitness right out of the box. I’m sorry gents, all I am used to is an EOTECH 512 and the Magpul BUIS, so my knowledge on the matter is rather limited.
For a “permanent” CQB fixture, I like LaRue: http://stores.homestead.com/Laruetactical/Detail.bok?no=29
For fold down, under a scope, like others, Troy.
The lower 1/3 cowitness is what you want if your want both up at the same time.
Thanks for the suggestion, too bad I am a full-time student at the moment and can’t get Larue until I enter a new tax bracket 
Why would I want the lower 1/3 cowitness if I am running both at the same time?
Thanks,
Dan
field of vision - a higher mount and ability to move your head more readily around gives you more flexibility with your red-dot sight, especially with fluid situations, body armor, barriers, bad postionss, etc. Having your BUIS in the lower 1/3 keeps that natural gravitation of your eyes away unless you have a problem. The irons are not making your FOV cluttered nor out of the way if you need them. A better balance and less rigidity.
We don’t know what system you are running. This post will probably read on a more basic level than you need, but I don’t intend any condescending or simplistic tone. Please don’t take it that way… I’m just thinking things through and trying to help even without some important facts.
I’m going to make two assumptions. First, you have a flat-top, not a fixed carry handle. Second, you do NOT have a funky rail like the CASV installed, which raises your rails across the top of your upper receiver, which can do funky things to how things line up.
IF you have a front sight post, obviously you have a front sight already, and will only need a rear. If not, you need both. You know this - like I said, I’m typing out my thought process, not calling you stupid. When you mentioned “Magpul system”, it hinted that perhaps you need both. There have been some pretty good reviews of Magpul’s MBUS sights on this forum. I have not actually run a pair, but I have seen them on another M4, and I thought they were fine. I personally run the TROY sight. To my knowledge, it makes no difference what BUIS you run - they will line up and can be sighted in.
You said you were running the Aimpoint M4. Great sight. The stock mount that comes with it will allow you to set it up as either absolute or lower 1/3 co-witness. If you want absolute, turn the sight over, unbolt the mount, take out the spacer, and bolt the mount back on using the shorter bolts that were included. If you want lower 1/3, it will be set up that way straight out of the box.
Sight in your irons, put your M4 sight on, and sight it in separately. Makes no difference what BUIS you are running - they’ll co-witness.
The nature of the Aimpoint sights is such that where the dot is, the bullet goes. That’s the beauty of the parallax-free design. You don’t have to line up the irons and the red dot to be accurate. THAT is the reason people are suggesting lower 1/3 co-witness - so you can rapidly acquire a target accurately through your sight while looking over your iron sights. You have more clear glass to see through - especially if you have a fixed front sight or fixed both sights. Think of it this way - you have a great view from a big picture window - why cover half the window with a couch? You will rely on your red dot independently much more than your irons, or you’re sacrificing the benefit of it.
Bottom line - you have a kick-ass Aimpoint. You’re installing back up sights as a redundant, back-up system. It doesn’t really matter what you use, as long as they’re quality parts. The Magpul MBUS set is pretty inexpensive, folds out of the way, seems to be reliable based on others’ reviews… it will probably be a good solution for you, especially if you need both front and rear, and you’re trying to keep cost down.
Than you for the response, you answered all my questions.
I’m not running a RDS now, so maybe this will be clear once I buy one - but if the stock Aimpoint mount is so versatile, why does nearly everyone buy a mount for it?
I can’t answer for everyone, just for me.
I didn’t like the way the factory mount integrated with the rail - a big knob sticking out the side. (I went with the M4s over the M4 due to the lower profile of the battery box, too.) I personally wanted to go with a lever-release quick-disconnect. I did some research and asked some questions here, and my choice was the BOBRO mount. I feel it’s more stable, and has proven to be very close to dead-on after being removed and reattached a few times (not that I plan on doing so again, but tested it to see - the sight stays put). I hope to never have two things happen… first, I hope never to have to use the carbine in a defensive/offensive role, and I hope nothing ever happens to the RDS. IF, however, both happen at once, I can ditch the sight completely in a heartbeat, and go back to irons.
Does that mean that the factory mount sucks? No… lots of people run them that way, and seem to be fine. In fact, my wife is contemplating some form of Aimpoint or other (M4 vs. T1), and very well may stick with the factory mount - but she’s not as active a shooter nor is she as tactically minded/concerned as I am.
EDIT TO ADD:
The factory mount for the M4 or M4s is actually 2 parts - the mount itself, and a spacer piece. It comes from the factory with the spacer installed. Also included is a pair of shorter screws in case you want to remove the spacer. The BOBRO mount I used only replaced the factory mount portion. I still used the spacer and the long screws, with a little drop of rockset threadlocker.
You’re most welcome. Glad that was helpful.
I have the CASV and love it, I run the CASV with an AIMPOINT and a ARMS mount and get a 1/3 cowitness without having to buy a tall mount for the AIMPOINT, and the AIMPOINT dont look like a satelite sitting on top of the rifle. In my opinion the CASV is the perfect setup. I am also using the TROY rear flip up site and everything lines up great. Also with both eyes open looking through my AIMPOINT i dont even notice the front site. So i wouldnt knock the CASV. VLTOR makes great products. The CASV also gives you a freefloat barrell. The CASV system was designed by the navy seals so i dont think its a funky rail system.
Easy, bro… no need to get your knickers in a bunch. I’m not knocking the CASV. I was just saying that the CASV does change the dynamic of the upper rail by raising the whole section except where the BUIS goes… so my advice to the poster wouldn’t necessarily work.
Plus… it was designed by the Navy SEALS…
Larue LT-103 buis & Larue m-4 lower 1/3 cowitness mount.