Can I put my BUIS here?

[East River Guide]

I've been shooting for many years but only just recently caught black rifle disease. So I bought my first one and was setting it up last night but since I'm new at this I was experimenting with the set up. I was told the rear BUIS goes as far back as possible on the rail and the scope goes in front of the sight, but I was wondering if anyone ever puts their BUIS in front of the scope (see photo below). Maybe non-standard, but here's why I ask:

1. I like the eye relief on the scope when it is further back. I'll be using the scope 99.99% of the time so it seems appropriate to put the scope where I want it, not where it fits based on the BUIS location that I will hopefully never use.

2. A mid-rail rear sight location is actually closer to how it is on my other rifles (e.g. Rem 700). When I mount it all the way back on the rail the sight picture isn't as crisp or as tight of a sight picture (even with the small rear aperture) as it is when I mount it mid rail. I understand it is a shorter sight radius, but it seems to work and besides, it's only an emergency back up.

3. It's easier to work the charging handle without the sights folded down on top of it. Not a big factor but again 99.99% of the use will be with the sights folded down so why not do what works best with them folded?

So just curious if anyone else has done anything like this or I am missing a compelling reason to put the rear BUIS all the way back and bump the scope forward. Thanks!

[Duffy]

I've seen users of the older ELCAN put their backup sight in front of the scope, the BUIS seems to be made to install in front of the ELCAN.

Nothing wrong with it, the reduced sight radius shouldn't matter that much in a backup sight



The blurry rear sight aperture is supposed to be blurry, it's "ghosted" because it's so close to a shooter's eyes. You're supposed to concentrate on the front sight anyway. Unless the rear sight is mounted mid-point, like an AK's rear sight, for instance, it's going to be ghosted.

Since you have a 3.5X TA11 with generous eye relief, I'd mount the rear sight behind it and move the ACOG forward. With the TA11 mounted so close to the rear, you have to extend the stock all the way out. I can see why you might want to do this with a 4x32 ACOG (1.5" eye relief), but not so with the TA11.

[Scoby]

Two reasons I wouldn't do it.

It shortens your sight radius between the front and rear. Have you tried using the gun with the sights mounted like this? I would think the rear peep would be really small and hard to pickup. May or may not be a big deal for you.

I always understood that bridging the upper receiver and the handguard with an optic or sight wasn't a good idea due to possibility of movement between the two.

If it works for you, great.

[a0cake]

By collapsing the buttstock a bit, the ACOG can be pushed forward just enough to get the rear BUIS in the back without compromising eye relief to suit your individual form.

OR, you could leave the buttstock fully extended and rethink your mechanics. I'm not saying Nose To Charging Handle is the be all, end all (it's just a way to be consistent)....but I see a lot of shooters wanting to be backed off too far. I honestly can't imagine needing the ACOG to be that far back and you still using correct form. Try leaving the stock extended and leaning / driving forward into the gun a little bit. It's hard to explain without actually being there.

Aperture type sights require the rear peep to be close to the eye to work. The rear sight is supposed to be fuzzy. You will naturally center and focus the front sight in the aperture, allowing it to fade away in the vision without consequence. That's how it's supposed to work.

Mid-mounted open rear sights are generally leaf or notch type sights, which work on a different principle and do not need to be close to the eye.

Bottom line is yes, the way you have the BUIS pictured is wrong. In this case there is a right and wrong and you can't just chalk it up to individual preference.

[MistWolf]

My first reaction was to tell you the BUIS is mounted too far forward. After thinking about it for a moment, three things occurred to me. First, the chances of the ACOG failing are slim to none. Not impossible, of course, but it's a very slim chance that you will find yourself in a life or death situation with a failed ACOG.

Second, while having the BUIS forward like that is not ideal, it's not unworkable either. The rear sight of the 03 rifle is mounted on the barrel and when flipped up, there is an aperture available for precise long range shooting. The diameter of that sight, I believe, is smaller than the aperture of your BUIS.

Third, whether the BUIS is forward or aft of the ACOG, the optic will need to be removed before the BUIS can be engaged anyway.

All that being said, your best option would be to see if you can push your ACOG forward enough to make room for the BUIS to be mounted as far aft as practical. I have very little experience with ACOG optics, but the few I have looked at had a short eye relief. However, if you hold your head upright and bring the rifle to your eye when you mount it, it will place your face closer to the charging handle. It's the proper way and faster than tilting your head to the rifle and means the ACOG will need to be pushed forward for proper eye relief anyway. I bring this up because shooters who tilt their head to the sight instead of holding their head upright and bringing the sight to their eye tend to place their face to far back on the stock. It's my experience that when using a stock that's too long often gives the same results- the shooter places their face too far back on the stock. As a0cake suggested, try shortening the stock a notch or two to see if that helps

[East River Guide]

Have you tried using the gun with the sights mounted like this?

Thanks everyone for the thoughts. Since this is a plinking gun and I figure the 0.1% chance of zombie hoards X 0.1% chance of ACOG failure leaves me with a low risk of ever needing the BUIS anyway, but even if I do this set up works pretty well. I get the part about moving the stock and I am sure you guys are right, but to me it's not worth changing my optimal set up 100% of the time to accomodate an option I would only use 0.01% of the time. I guess I could of skipped the irons altogether but, well, I didn't so hopefully this ends well.

And I tested it last night- the sight picture is good mid rail with the large aperture up. At 15 yards shots were touching, at 20 still inside a quarter, and at 30 yards I can't see a 4 inch target (only ones I had in the car) well enough over iron to really test it so I can't really say (but the ACOG was great). I think with some practice (this was first time I ever shot this thing) I can get it tight enough for emergencies. Besides, I was checking out some photos of the guys in Iraq with ACOGs and I noticed some don't even have any BUIS at all so if they can get by with none I'm sure I can make do with a mid rail set up.

[pilotguyo540]

It looks like you are shooting from a weaver stance with your stock all the way out. Maybe you are gigantic. Try shooting isosceles. I think that will change your entire configuration to a more "normal" setup. Someone already touched on this bit that should allow you to move the ACOG forward and put the rear where it belongs. It looks like your BUIS is mounted on your FF tube, it's a little hard to see on my phone. I would avoid that if you are serious about having back up sights.