View Full Version : Talk to me about backup sights

07-03-2008, 6:34 PM
Hi guys,

I'm just about in receipt of my first upper (CMMG 16" lightweight 5.56) and although I have a nice scope (Nikon), right now it's on a side-saddle, quick-release AK mount. I'm wondering what is a good quality back up iron sight that won't cost me an arm and leg. Best bang for the buck is what I'm looking for.

Some particular brands and models is what I'm looking for.

Also, is there a particular set up I could use that would allow me to use the same scope on both rifles that would keep the settings without having to reset?

Many thanks,

07-04-2008, 3:51 AM
I just built my first AR and i am missing a BUIS. I was actually going to post a similar question because i'm in the market for one also. I remember looking at the for sale forums and seeing some nice sights for around $60. Now, it seems impossible to find. Anyways, here's a bump because i wanted some input on this too.

07-04-2008, 10:21 AM
Are you going to mount a magnified optic? If so, you need to consider whether the BUIS will fit under the scope and mount/rings combo - some mounts (like the Armalite) are very low, and others (like the M1Sales) are quite high.

If it's for a red dot/Eotech style, there's a lot more flexibility.

For a magnified scope, you'll need a flip-up BUIS. For a non magnified optic, you can use a fixed sight as well, which is generally sturdier, but obscures part of your field of view.

A few things to consider when choosing rear flip-up BUIS, depending on if it's going to be a range gun or a SHTF gun:

- Will it be used for precision or long-range shooting? A small aperture is helpful for this. If the use is both close-up and long-range, a dual-aperture sight is useful.
- If it's multi-aperture, which one is deployed when it flips? Some flip with the large aperture deployed, others with the small. If you're not in a hurry, this won't matter, but some people care.
- If multi-aperture, do the apertures deploy in the same plane? Some deploy with an elevation shift to account for the range differences, others use the same zero for both apertures.
- Do you want the windage knob easy to adjust or shielded to prevent accidental adjustments? ARMS are exposed and easy, Troy is shielded.
- Does it have elevation adjustments? Some do (like the Wilson Combat), most don't.
- How easy is it to deploy or adjust if your hands are muddy or gloved?
- Does it latch in the up position, the down position, or both?
- How protected is it from damage, both down and deployed? The Matech is one that sticks up with little protection and can easily be tweaked or broken by rough handling when deployed.
- How robust is the detent mechanism? The Matech will wear over time and become easier to deploy (and eventually won't lock). For many, this doesn't matter, as their BUIS aren't used often.
- How many slots does it cover? This is important if you need to conserve rail space.

Figure out which of these are important to you and what capabilities you want, and it will narrow down the choices quite a lot.

Here are some popular BUIS heights:

ARMS 40 - 0.950" folded (mine is 1.00" even)
YHM-9680 - 0.840" folded (mine is 0.850")
Matech - 0.75" folded
MI ERS - 0.750" folded
GG&G MAD - 0.625" folded
ARMS 40L - 0.610" folded
Troy - 0.460" folded
MI MCTAR-SPLP - .4375" folded
KAC 300m - 0.315" folded

Here's how to figure out if it will fit under your scope and mount.

- Measure the scope's eyepiece diameter, with flip caps if you're going to use them. Butler Creek usually adds about 0.1" to the diameter.
- Divide that by 2.
- Subtract that from the centerline height of your mount or rings.
This gives the maximum height BUIS that will fit under that scope/mount combo.

I'm not aware of any mounts that would let you switch between an AR and AK without unmounting the scope. If you can put a Picatinny rail on the AK, you could get a QR mount or rings that would let you switch back and forth quickly, but getting the heights right might be tricky.

Regardless, you'd need to zero the scope on each platform and make a note of how many clicks difference there was between each, then re-adjust when you switch platforms. This would get you close, but no system will be zeroed on both guns.