Ignore my join date...  I recently bought my first AR, which is super basic (Ruger AR556), and which I only use for simple plinking at short and medium range.  Longer term I will look to build a more custom / fancy system, but for now I just want a decent optical solution for 400 yards or less that doesn't break the bank ($400 or less, but not necessarily a firm limit if there is a huge increase in quality slightly above that price point).

I have spent enough time trying to figure this out that I wanted to inquire of the wisdom of the hive...   This rifle has a fixed front sight, which I'd prefer to not remove, so I think I'm stuck with cowitnessing.  Here are some options I have been considering:

1. Vortex Optics SPR-1303 Spitfire 3x Prism Scope, Price $349.00 (e.g., Amazon)
One thing I like about this in particular is the ACOG-like reticle which seems to make ranging really efficient.  That would seem to give a decent versatility.

2. Vortex Strikefire II....   PSA has this with 10 PMAGs for $179.00 right now.  It's just a 1X but I've seen people put a Vortex VMX-3T 3X Magnifier ($199.00) in series with it, which can flip out of the way.  This gives (as above) a total 3X option for around $379.00 (or $300 when PMAGs are subtracted out), but without the nice reticle I guess.  Alternatively, there is the SPARC II instead of the Strikefire II for about $20 more.

3. Option 3 is variable scope--not sure where to even start here.

Maybe I'm overthinking this.  Any help would be much appreciated...

I have hit steel IDPA targets out to 300 yards with my aimpoint pro. 400 yards with an AR-15 like the ruger ar556 is getting sketchy to me. 400$ should get you an Aimpoint Pro which is LEAPS AND BOUNDS better than any Vortex red dot.

Disclaimer: I have 20/20 vision

3-9x variable in high rings if you're just going to plink/hunt w/ it.  If it's a HD/truck gun, then you'll want a red dot or a 1.n-Yx variable.

Just something to think about on your Option 2 - Vortex gives you a 2x magnifier that screws into the rear eye piece so you could get extra magnification without extra cost.

The Vortex is a great buy for the money, but being honest it is not a combat rated optic like an AimPoint...

I always felt silly paying as much or more for an optic as the rifle itself...

You can hit with a RDS at a very surprising long range.   I've shot the distance with an Mforgery 16" Carbine using M68 Combat Optic (4 MOA AimPoint M2) at 400 yards Known Distance Range (4" group x 4 hundred yards = 16" group) which will keep it on the target and is about what the average non-free float AR will shoot with Ball - GI Type ammo.

Keep in mind if shooting at distance, say 400 yards in your example, the size of the dot of a red dot optic can be critical. One of those you listed has a 4moa. Which is roughly 4" at 100 yards. 16" at 400 yards. Take Tig's example of a plate 18" square. If your red dot was dead center on the plate, only the outside 2" of that 18" would be exposed (generally speaking). Depending on your vision and at what distances you feel will be your norm, you might consider a 1x6, etc low power scope. Once you start pushing pass 3x with your scope, the fixed front sight pretty much invisible or just a very light ghost (non-distracting) of itself. If you go with a scope of that approx size, it'll likely have an eye relief of around 3.5" or so. Therefore, when you consider an average overall length of the optic to be somewhere between 9-11", you might also want to consider a cantilever mount. Then you have things to consider with a variable scope / fixed front sight situation like during dusk / dawn there will be less light entering the scope if it isn't mounted above the front sight, etc. Even tough at the moment you're only wanting to invest approximately 400.00, there's a lot to consider so that you don't regret having spent your hard - earned 400.00. The red dot with a 3x isn't a bad idea however you'll likely want a flip mount for the magnifier. A good magnifier and mount can get costly. Not insane costly but I'd say you could easily have 600.00 (at a lower level). There might be some pkg deals out there and perhaps a nice labor day sale is right around the corner. Black Friday / Cyber Monday sales will be here before you know it if you have the patience. If you're fortunate enough to live in an area with gun stores who carry AR15 carbines , red dots, scopes, go there and try a few combos so that you can make an informed decision. EZPZ.

Thanks all--I need to give this more thought, clearly!

Also, to clarify, I'd really be spending most of my time plinking between 50-200 yards, so the 400 is really an absolute max.  This would also double as HDR until I upgrade entirely, hopefully within a year or so.  Thanks for the ideas to mull over...

Another option is a low powered variable, which could give you some up close usability as well as some magnification for distance.

The Steiner P4xi has been getting very good reviews and can be had for only a little over $400 IIRC.  It's a 1-4x scope with daylight bright illumination and very good glass.

Now that you've shared a bit tighter picture of the weapon's intended usage, I'd give serious consideration to the Vortex red dot / Vortex 3x magnifier combo on a flipper. Believe you'd really like that. Another thing I do with a dot and several other things in life is I'm heavy on visualization. For example, the dot is now covering 16" on an 18" target. If all is well on the mechanical side of the house, I can pretty much "visualize" the center spot behind my fat red dot. Some folks find it a bit peculiar but that's ok. it works. Gotta give credit where credit's due. A Canadian sniper put me on to that back in 2001. Which reminds me. They had much better rations than the U.S. stuff.  A really good way to practice this is to zero the weapon to 100 yds and set up a series of coke / beer cans filled with water, sand, etc for stability. A 12oz can is normally a spit over 2.5" diameter at the center point. This is a good size to practice on with a dot ranging from 2-4 moa and/or a circle with 65 moa. It makes for an excellent starting point. Or if your range is limited in distance, you can do it proportionately at whatever distance you choose. I reckon if you do it closely enough, a simple circle / dot on paper would be fine since you can easily see it under 30 yards or so. You will quickly be "looking" through the dot. Once you're satisfied, either back up you position some or go with smaller "hard" targets. Single eye / both eyes; works either way.

That's a nice alternative for sure. I need one. I need one of everything. Damn internet!

I love mine its the LPV that's making me think about having an LPV for a HD rifle optic. Fair weight, good feature to price ratio and the perfect magnification range for me. It's closer to $500 (bit under) than $400.

Pretty compact. My Viper PST was about 1/2" shorter and an ounce less. A lot of scope for the money and size.

Thanks all!  Went with the Steiner P4Xi.  Found it for $465 and free shipping, after reading and watching a variety of (very positive) reviews.

Good choice. Great mix red Dot and variable scope capability with excellent glass for that price point.

For your intended use an Aimpoint PRO sounds just about perfect.

Edit: just saw you got the Steiner. Also looks to be an excellent choice. Congrats

Congrats on the new optic. Can't wait to see it and perhaps a field report.

Thanks all--let me know if you have any suggestions for high quality mounts.  I guess there isn't much use in a good optic if it loses zero after 30 rounds.

Great choice for a first optic. If it had been my first choice I would probably have not tried so many others. Then again it wasn't on the market when I first got into ARs. 

I like the Aero SPR it's lightweight but it's fixed, if you want QD look at Larue or ADM. 

For my QD mounts I use Burris Pepr QD mounts. They are rock solid and can be found on sale for about 70.00.

Before selling, I had my Vortex mounted on an ADM Recon w/ QD (cantilever). I really liked it though it's a little bit pricey.  When you do mount the optic to rings, use the scope manufacturer's torque specs (if torquing) for scope to mount installation and not the specs provide by the mount company.

Astigmatism and red dots equals blurred dot. A prism optic really helps the dot definition.

The Steiner arrived--very exciting...

I'm leaning toward the AD Recon QD mount, but have a stupid/newb question:  how do I determine whether this mount will be tall enough for the P4Xi to sight above the fixed A2 (f height) sight on my Ruger AR 556?  Longer term I'm planning to build a different rifle (without FSB) so this will be moot, but in the meantime....  any advice?

If you mount the sight so high that you can see over the front sight, you'll have no cheekweld.  The Army just co-witnesses the front and rear sight through the red dot, so you'll see a big front sight in the sight picture - and you'll learn to completely ignore it.  Some folks use a lower 1/3 co-witness so they have a less busy sight picture.

He got a 1-4 optic.

Yep, missed that.  Advice is the same, though.  He almost certainly won't be able to use the sights through the optic, however.

You'll still want a "cowitness height" optic mount which is roughly 1.5" above the top rail.  You'll definitely see the FSB/FSP on 1x, but you just ignore it.  You'll see a slight shadow in the bottom of your FOV above 3x, but it doesn't affect anything and it essentially disappears if you don't focus on it.

Another thing, don't plan on actually "cowitnessing" your irons through the scope, it won't work with a magnified optic, even on 1x.

The presence of a FSB should not change your mount selection at all.

Thanks all--it makes perfect sense that the post will still show in 1x.  I was worried that I might inadvertently get a mount that sat so low that it would actually cover the reticle, or some other really stupid mistake.  But it sounds like the standard 1.5" center line is sufficiently high that this won't be an issue.