BUIS: flip up or static

[QuackXP]

When I get around to buying an AR-15 type rifle I plan on buying the rifle first and then a quality optic later and using the iron sights in between that time. This will allow me to learn to use the irons without becoming dependent on the optic and spread the cost out a bit.

I'm currently looking at models with a monolithic upper and an integrated rail. Top of the list is the Colt SP6940 and the LMT CQB16. The optic will most likely be an Aimpoint set in a lower 1/3 co-witness with the optic.

Now the BUIS is not the only difference between these rifles. But it’s the one I want to focus on for this post.

The Colt has flip up sights whereas the LMT has static sights.

Here is how I see the pros and cons.

Flip Up (Colt)
Pros
They stay out of your line of sight when using the optic.

Cons
In a defensive situation where you would have to fall back on them they would need flipped up.
Could get knocked down.

Static (LMT)
Pros
Has standard A2 type adjustments and two peep holes.
In a defensive situation there would be no need to flip up the sights. Just adjust for the slightly lower sight picture.
Not have to worry about them being knocked down.

Cons
You would see them in the lower 1/3 lower portion of your optic.

This does not necessary have to be a discussion about the sights on these two models. Experience with these sights on these models is a plus but a general discussion of flip-up vs. static would be fine.

[y0rlik]

Is there any particular reason you want a monolithic upper? If you go with one, you will be unable to swap out many parts on your own. If it were me, I would go with the basic configuration since it's more flexible/modular. The up-front cost is also lower for the standard configuration, and most people (myself included) don't need the amount of rail space offered on a monolithic upper.

As to the BUIS, unless the fixed BUIS really annoy you when looking through the optical sight, I would probably go with those. They are simpler mechanically, and that means they are more durable and probably less expensive.

[QuackXP]

Is there any particular reason you want a monolithic upper? If you go with one, you will be unable to swap out many parts on your own. If it were me, I would go with the basic configuration since it's more flexible/modular. The up-front cost is also lower for the standard configuration, and most people (myself included) don't need the amount of rail space offered on a monolithic upper.

I'm not worried about being able to swap parts on this rifle. It is going to be my go to defense and SHTF rifle. I want a quality pre-build rifle that I will not have to make any major changes to. If I ever have an issue with it (hopefully not with Colt or LMT) I want to be able to go back to them and have them fix it without worrying about what my mods did. The monolithic upper appeals to me to flexibility of adding the top optic anywere I want as its one solid row of mount points. Also the accessory rails are sturdier.

Down the road I will probably build a project rifle that I will leave open for upgrades and changes.

Back to BUIS discussion.

[bac0nfat]

I have fixed (or static, whatever you want to call it) iron sights on my AR. But I can think of one definite advantage of switching to flip-up sights: You don't need a riser for your red dot, allowing for a better cheek weld. Unless you are happy with fixed irons and absolute co-witness, which I absolutely hate. Too much clutter in the red dot window. Down the road I'll probably ditch my fixed irons, ditch my riser for the eotech, and get flip-up sights.

[vicious]

Just remember that if you need to switch to your BUIS, it is more likely because your optic became occluded (by damage or debris) rather than ran out of batteries or had an electronic failure. This means it will not be as simple as just switching to your BUIS. You will likely need to ditch your optic in a hurry to see your sights even if they were cowitnessed.

More important than what kind of BUIS you choose is to make sure your optic is on a quality quick detach mount.

[QuackXP]

Just remember that if you need to switch to your BUIS, it is more likely because your optic became occluded (by damage or debris) rather than ran out of batteries or had an electronic failure. This means it will not be as simple as just switching to your BUIS. You will likely need to ditch your optic in a hurry to see your sights even if they were cowitnessed.

More important than what kind of BUIS you choose is to make sure your optic is on a quality quick detach mount.

For mount I was looking at LaRue or similar. In that case with flip up it would be a two step process to take down the optic and put up the sights.

[QuackXP]

I have fixed (or static, whatever you want to call it) iron sights on my AR. But I can think of one definite advantage of switching to flip-up sights: You don't need a riser for your red dot, allowing for a better cheek weld. Unless you are happy with fixed irons and absolute co-witness, which I absolutely hate. Too much clutter in the red dot window. Down the road I'll probably ditch my fixed irons, ditch my riser for the eotech, and get flip-up sights.

Never though of it that way.

[Asmodeus6]

I prefer flip ups. Deploying them isn't as bad as you would think. Some are better than others.

And it gets them the heck out of the way, or allows any configuration you end up liking best. (RDS and FSP without the rear) None, just RDS... etc.

Flip ups usually cost more, but are more versatile.

If you mount your optic on a QD mount, it will already be raising it up most likely. The good mounts are designed to co-witness.

I have fixed (or static, whatever you want to call it) iron sights on my AR. But I can think of one definite advantage of switching to flip-up sights: You don't need a riser for your red dot, allowing for a better cheek weld. Unless you are happy with fixed irons and absolute co-witness, which I absolutely hate. Too much clutter in the red dot window. Down the road I'll probably ditch my fixed irons, ditch my riser for the eotech, and get flip-up sights.

Do you know how well two head positions work on one rifle? IE: Have you actually tried this with the RDS that low on the rail?

Because I have, and it sucks. Not only do you have to squish your face down low enough on the stock that you get horizontal phasing on the dot in the RDS. But having two head positions for the same rifle lends itself to no consistency. This is generally accepted as a bad idea.

Repeatable head position = faster sight alignment with a consistent POI.

If you don't like the absolute cowitness, do a lower 1/3rd. But have your head in the same place either way.

[silverado_mick]

I have flip ups from Troy on my work rifle and have used a fixed front with a rear flip up from Yankee Hill Machine as well as the issued rear flip up from MaTech behind an ACOG. Both setups worked well and even though I prefer both front and rear flip ups I have no problem with a fixed front sight post. If you are using your RDS properly you will harldy even notice the front sight post in the window.

While I have never had to deal with a fixed rear sight behind an optic I have a feeling that I would hate it. Like others have said, too much clutter. I also must say that if you are worried about durability, don't. As far as flip ups go both the Troy and the YHM sights I have are stoutly built and have taken and continue to take a beating. They deploy simply and in under a second, and there is no way to get them to fold down without releasing the latching mechanism. I have the utmost confidence in them, and I don't use gear that I don't trust my life to.

I would absolutely recommend Troy or YHM as well as LaRue for any of your AR rail mounted accessories.

[QuackXP]

OK total newb question.

RDS = Rear ? Sight
FSP = Front Sight Post ??

Am I even close?