There have been a lot of optic threads lately. I took a chance on an Omega Manufacturing fixed 4x scope. This is my honest and realistic review on it. It's worth the read, as this is a great optic for the money. Here's an Amazon link. EBay also sells it for cheaper.
Amazon.com : OmegaMfg Tactical 4x Prismatic Rifle Scope Mil Spec Chevron Reticle : Sports & Outdoors@@AMEPARAM@@http://ecx.images-amazon.com/images/I/311QVT8TqvL.@@AMEPARAM@@311QVT8TqvL

Picture of it on my 15-22


Pictured next to my AR with the Burris AR-332


Review I posted on Amazon:
I bought this for my M&P 15-22. My goals and expectations were realistic and very calculated. I wanted a fixed optic similar to my true AR setup. I am using the Burris AR332 on my AR, so my comparison for quality and functions is up against a quality optic costing nearly 6 times as much. Being that my 15-22 only cost me $300, and the fact that I'm going to be abusing the weapon as a trainer for my real AR, I wanted a cheap optic that had a similar fixed power and wasn't going to cost the same price as my rifle. This optic fits the bill very nicely with only a few issues to address. First, however, the good.

-The optic is very clean looking. Mated up to the weapon, I can't get over how nice it looks on my rifle. As another reviewer mentioned, it's not overloaded with tacticool **** you don't need. It's clean and it serves a function. That gives it immediate out-of-the-box appeal.

-When considering an optic, two of the most important things you must consider are glass clarity and light transmission. The clarity is acceptable. It's not impressive on it's own, but once you consider the price, it's quite good. I never find myself wishing for better on this weapon. Again, I'm comparing this to a much more expensive optic. Next, light transmission. Wow! It is nearly as bright as my Burris and actually very impressive. This was one of the most compelling things about this optic. Both clarity and light transmission and superb at this price point and hard to beat.

-Reticle. The chevron style is far from my favorite but it works well. The etched glass is great and requires no lighting for use outside. It's also nice to have zero reliance on batteries that fail. The reticle is crisp, clean, and easy to acquire. Because of the chevron style, don't expect to shoot or acquire targets with both eyes open. It can be done, but not well. My Burris has a CQB reticle that makes two-eyes open shooting possible and enjoyable. You will require a back-up system for close quarters work if you want to be quick about it. That is to be expected, however, once you get into magnification over 2x. Because the Burris has the CQB reticle, they defy this fact. This optic, however, will not allow you to shoot with both eyes open.

-Zeroing. The optic has held zero. The adjustments are crisp and clean. It does what I'd expect a more expensive optic to do. I was drilling the same hole repeatedly at 50 yards with **** 22 ammo. I'm sure this would hold up and do better on a 223/556, although I would question the recoil only slightly. I mounted it, like every other accessory on my AR, with blue Lock-Tite.

The areas needing improvement:
1. The eye relief is terrible. I shoot nose-to-charging handle style anyways, but effective eye relief is only 2" at the most. That means with my scope mounted on the rail closest to my charging handle, my nose is nearly touching my handle. This for me, is the worst part. A full day of shooting makes my neck hurt a little because I have to adjust my natural stance. I'm 6' tall with a muscular build, so this may have an affect on me that may not bother other people of a different stature. Field of view is very similar to the Burris, which means it's very good, especially considering it's a 4x versus the 3x Burris. With all of this being said, it does allow me to pick up my AR and feel super confident and proficient as the Burris has superb eye relief. That is my goal with the 15-22 anyways.

2. The lit reticle is really cheesy. This is the only place where I feel like I can tell I bought a cheap optic. The different brightness settings make little difference in the appearance of the reticle. It also shows the tiny imperfections in the chevron. It has three colors, so that's cool. The lit reticle is entirely unnecessary so it doesn't steal a star away. I'll consider using it in low-light scenarios, but again...it's hardly going to be used and doesn't have any bearing on my overall impression of the optic.

3. Some lens covers would be great. There's no way to protect the lenses. I store it with a snowboard goggle cover that cinches. That works. Again, nothing to take away a star. There's no way to add covers to this style that I'm aware of.

Overall, this is a great buy. I'd be truly disappointed if I got this for my AR simply because there are better options, be them far more expensive. I believe in buying an optic that costs a good deal close to 1/2 the price of a rifle as a starting point. For my 15-22 trainer, this is the perfect magnified optic that lets me train close to my AR. Now, I just have to add 45 degree rails with irons or a micro RDS for CQB action. I'd cautiously use this on an AR, but again, the AR is a defensive weapon that deserves a quality optic. I'm not grabbing my 15-22 unless there's a zombie squirrel invasion. Hope this helps. Don't hesitate to buy.

Looks like you have the scope as far back as possible, but you know you can get an offset riser mount that will allow you to move it further back. It just might save your neck muscles.

Bob

Thanks Bob! I'll look into it. I presume it will interfere with the charging handle, but I'm looking into it right now.