Due to the design of the AR, the proper cheekweld is achieved with the center of the irons and optic at approximately 1.5" above the rail. It's possible to lower the optic so that it's closer to the bore, but at the expense of be able to actually get the eye centered behind it.....so it's simply not done.

If the optic mount isn't removable without tools, then installing offset irons is the only valid option.

The time required to remove "QD" mounts varies quite a bit. Some, like the Scalarworks, should be called tool-less, not quick. Others, like the ADM Recon, Midwest Industries mount, and LaRue LT104 can be removed and BUIS deployed within about 8 seconds. The tighter the levers are locked to the rail, the longer it takes to apply adequate leverage to unlock them. In my experience, the fastest ones to remove are the Bobro followed by Midwest Industries. The Bobro is really fast to remove, but the design doesn't seem nearly as robost as the others.

I recently purchased my first set of offset irons, which are Dueck Defense Rapid Transitions. They're as easy to use as an A2, fully adjustable for elevation, and can be transitioned to very quickly.

Ya, offset irons aren't aesthetically pleasing, but my gear doesn't go to beauty contests, so that doesn't matter.

 

A2 front GB/sight, and a BUIS flip on rear, + scope.

If the goal is to try and retain same grip and hold between using scope and iron, then co-witness the two. Otherwise just mount irons and a scope, then zero each on target.

 

With a 20" barrel, the back-up sights are definitely a secondary sighting source. I'd go with the back-up offset/slanted sights from Magpul or Midwest Industries.
I'd put some decent glass on it if it's going to be a long-range/sniper gun. Get it from Larue with their discounted prices and then whichever of Larue's excellent mounts you pick the mount will be essentially free.

 

Why mount BUIS on angle? If they are flip style, then why not just std mount?

 

I’ve tried to make 2 objects occupy the same space, but have failed so far.


The OP could buy an extended eye relief scout-style optic in the handguard, in front of the folding BUIS, but that would be a really bad idea.

 

Not everyone is willing to have a backup iron solution that takes over 5 seconds to deploy. The original poster in this thread seems to want to be able to instantly transition to irons, and that’s not possible with a folding rear below the optic. There is solid reasoning behind this.

Folding offset BUIS exist, so they’re at least not hanging too far off the side of the rifle, so they only take a couple seconds to unfold for use.

 

Not everyone is willing to have a backup iron solution that takes over 5 seconds to deploy. The original poster in this thread seems to want to be able to instantly transition to irons, and that’s not possible with a folding rear below the optic. There is l solid reasoning behind this.

Folding offset BUIS exist, so they’re at least not hanging too far off the side of the rifle, so they only take a couple seconds to unfold for use.

Sounds a bit Steven Seagal'ish, but whatever floats the boat.

 

Seems like a whole lot of scope for an $80 barrel.
Be interesting to see how this turns out.

I spend the absolute most I , or the client can afford on the barrel,
Especially if building a rifle , 20” or more gun. And expecting long range accuracy. It gets expensive.

the m16a1 and a2 ran iron sites, on a 20” and was standard issue for many years. 20” is Pretty standard for a rifle AR.

I would personally go with an optic 1 to 6 or so on an AR. Or a simple 4x , And long eye relief, you will need it, And know the scoped cheek weld sucks on an AR. It just does. If you’re used to say a rem 700. Want long range cheep, buy a rem 700!

I kinda think you are under barreled, and over scoped.
If looking for a long range gun,
And will have eye relief issues. It’s best to get an AR style scope, a bolt gun scope does not work well with an AR. I would look at primary arms for a lower cost AR optic options. Make sure if using a bullet drop type scope it matches barrel twist and the round best suited for that barrel.

also if building for long range, I would make sure the upper area that goes into the barrel extension is square as possible and mirror flat, no machine marks, and that the barrel extension and upper are a almost press fit.
Use stainless steel shim stock of the appropriate thickness to make it that way if needed. It’s cheep get different sizes and make it concentric as possible.
A little trick learned at camp perry. It works.
Just my opinion.

 

Seems like a whole lot of scope for an $80 barrel.
Be interesting to see how this turns out.

I spend the absolute most I , or the client can afford on the barrel,
Especially if building a rifle , 20” or more gun. And expecting long range accuracy. It gets expensive.

the m16a1 and a2 ran iron sites, on a 20” and was standard issue for many years. 20” is Pretty standard for a rifle AR.

I would personally go with an optic 1 to 6 or so on an AR. Or a simple 4x , And long eye relief, you will need it, And know the scoped cheek weld sucks on an AR. It just does. If you’re used to say a rem 700. Want long range cheep, buy a rem 700!

I kinda think you are under barreled, and over scoped.
If looking for a long range gun,
And will have eye relief issues. It’s best to get an AR style scope, a bolt gun scope does not work well with an AR. I would look at primary arms for a lower cost AR optic options. Make sure if using a bullet drop type scope it matches barrel twist and the round best suited for that barrel.

also if building for long range, I would make sure the upper area that goes into the barrel extension is square as possible and mirror flat, no machine marks, and that the barrel extension and upper are a almost press fit.
Use stainless steel shim stock of the appropriate thickness to make it that way if needed. It’s cheep get different sizes and make it concentric as possible.
A little trick learned at camp perry. It works.
Just my opinion.

I'm building it for long'ish range. About 500 yards max on a good day. Thing is that I don't have a range nearby that's 500 yards (at least I don't think so), so right now nearly any scope will do.

The build is coming 1st, make it into a handy all around AR for now, fine tune it with a better scope later.

I can always put the 1st scope in another build.

As for the barrel, we'll have to wait and see. I've seen budget components do incredible things. This one is stainless steel, so I think it'll be fine.

Recently saw a video of a guy with a cheap parkerized 223 Wylde barrel hit subMOA at 100 yards, depending on the ammo. Which makes me think that often times the ammo is more accurate than the gun is.

 

For iron sights I like the Magpul MBUS pro flip up sights. As far as scopes I like the Trijicon ACOG 4x32 and the Vortex 3x prism scope, the Vortex Viper. Bushnell makes a couple good scopes too. For some more money look at EOTech.

 

I've decided to sit on getting a long range scope for the build for the time being. I want to see how it shoots 1st. Going to put one of my cheap scopes on and see how it shoots at a closer range, what the grouping looks like and such. If it shoots a good group, then I'll invest in a better scope and see what it can do at longer ranges.

I've also decided to go ahead in invest in fixed, offset sights. I think they're the best option.

Still working on getting the rest of the parts. Still have to buy a handguard, gas tube, BCG, and charging handle.