AR's are probably the best assault rifle-based rifle available right now. The upside of the AR is that there are an incredible number of options and ways to set 'em up. The downside of the AR is that there are an incredible number of options and ways to set 'em up. Any site on the web that has the capability of posting pics of guns almost certainly has photos of AR's on it. Some are set up well...and some are better termed Football Bats than carbines.
My intention is not to dwell too much on brands, as I intend to rant on the set up rather than on the particular model. Up front, I have to state that my carbine is what I would term a Frankengun, and I have blogged against parts guns for best reliability. I do need to make a couple of comments on this subject, though: first, "just as good as" doesn't exist unless you're comparing guns built on or as close as possible to the TDP (Technical Data Package). Gun prices don't exist in a vacuum, and Daniel Defenses, BCMs, Colts, LaRues, LMT's, Noveskes, Knight's's...'s, and their brethren aren't just more expensive to be more expensive. Not all parts are created equal, and quality isn't free. Are you paying for a name with Tier 1 and Tier 2 brands? In a sense you are, insofar as you're paying for what the name represents. Reputations are built, not awarded. You're paying for the name that is based on the reputation built on quality. A Bushamster or DPMS or other commercial spec gun isn't the same. It can't be; it's not built to the same standard with the same quality parts. How to determine which is the right gun for you is a blog for another time.
For simplicity's sake, assume that the base gun is a duty-quality carbine with properly staked gas key, staked castle nut, Mil-Spec parts, and the like. That way, I can limit this epic tome just to set up and external parts and accessories. And of course, this is a way, not the way. OK, it is the way, but there are other ways that are the way, too. And there are lots of ways that aren't the way. Don't do it with the not the way. It's called "not the way" for a reason. Not the way often has plastic parts from one of the 78,000 Israeli companies that make crappy parts for the AR, which falls under the blessing/curse clause of the AR mentioned in the first paragraph.
If you're starting from scratch, consider the 14.5/permanently attached flash hider (to make it a 16", non-NFA legal barrel) and mid length gas system. There's nothing wrong with the carbine gas system, but the mid length is a little smoother, softer shooting, and probably wears parts slower. In terms of front sights, I'm a believer in the Front Sight Base rather than rail mounted folding sights. The "why" is that if your optic goes out due to failure or the battery going dead, you can make surprisingly accurate hits using the front sight post. Your rear sight becomes a giant aperture sight at that point, meaning out to about 25 yards, put the front sight post on what you wanna shoot and press the trigger to the rear. At that distance, you may or may not have time to flip up your back up sight. If you have time, do it. If you don't, put the front sight post on your target and nail it. The reason I prefer the FSB to rail mounted sights is that as long as the barrel is properly indexed, there's just less involved with a pinned FSB vs. other screw-on sight systems. Pins are a big enough deal that I've become a believer in grinding down the FSB rather than using a set-screw low profile gas block.
The great thing about fore ends is that there are a ton of great choices now, and where there were lots of choices of the 7" rail before, now it's possible to go longer with a few different choices. There are two advantages to going to a longer rail, and 12"-13" is the magical length. The "why": those two advantages are that you can grab the fore end further out. The closer you can get your hand to the muzzle, the better you can control recoil. The other advantage is that you can get your light further out, which means less shadow caused by the barrel. Some lights can even be mounted in front of the FSB, which means less leaning out from cover to get the light shining where the target is. In terms of rails, I'm a huge fan of Daniel Defense. Their stuff is always in spec and are the lightest rails going. I don't recall ever hearing about one being broken under normal circumstances. There are, of course, other quality rails, but I always recommend DD. Light, strong, in spec and easy to install. How can it get better? Their 12.0 FSP Lite rail is the standard of excellence for rails.
However! Now there are some options for fore ends other than full rail systems, and they're less expensive to boot. There are tubular handguards that can still mount lights by adding sections of rail where they're needed. Note the light on my home boy Paul J.'s VTAC fore end:
The VTAC is really light, slim and comfortable. Troy makes a nice 13", called the TRX Extreme, and it's MSRP is only $189, which means that it can be had for less "on the street". Like the VTAC, it can use bolt on rail sections. Ignore the vert grip in this pic, it's in the wrong place. The pic is Troy Industries's...'s:
As I said, that's not my preferred sighting set up, but it beats the hell out of no front sight at all, and there are advantages to having a clear sight picture, too. For Pete's sake, run that vert grip out to the end of the rail!
I very much prefer the Surefire M300 Mini Scout with theSR-07 switch. This system keeps the light and the switch out of the way, and means I have to move my thumb about a half inch instead of changing my grip to reach the light.
Previously, I've used the tail cap and actuated it with my support hand knuckle. This allows me to use the thumb over grip without much other change. Changing as little as possible makes everything easier, smoother and more consistent. Related to all this is sling placement, which I'll address a bit later.
Working backwards, we come to the upper receiver. Some people like to have AR's with carry handles, no lights and optics, and call them "KISS rifles". KISS stands for Keep It Simple, Stupid. The fact is, that's not simple, that's less capable. Flat tops are the only choice for a real fighting gun, because simple only needs to apply to the mount for the sighting system. Choices in optics are simple, too: get an Aimpoint. There is much to love about the Eotech reticule, with the dot and circle sight picture. However, on the whole they just don't last. Some can go to very high round counts, but most don't seem to be able to do that. I've got a friend who's XPS2 crapped out within 12 rounds, shutting off and not coming back. Another friend has about 7300 rounds on his, and his zero has started wandering. An 18B friend of mine DX'd (sent back as broken) 32 of them, on a 12 man team. Others have reported exceptionally high failure rate amongst their duty guns. I dig the XPS series, but they're not lasting a whole lot better than the older sights. If the gun may be used for serious purposes and not just a range toy, get an Aimpoint. My M68 (old style Comp ML2) has been on two deployments before it went through the DRMO system and given to me. Still works fine-now that there's a battery cap on it-and holds zero like a vice. Almost everyone I know that runs one has trouble free performance. It's just cost-effective insurance.
What about mounts? There are plenty of good ones, but LaRue Tactical is still the best of them. They have a new no-lever mount that saves about $25, so if you don't intend to move the optic, get the VFZ version. They're the best there are, no more expensive than other good mounts, and ya get a bunch of cool stuff with the order. Can't beat 'em. If you're using an M68 CCO mount, use the LT-150, which gives a 1/3 lower co-witness. One reason for going for the throw lever mount is that if your optic gets destroyed somehow, you can dump it and go to your BUIS. I mount the optic as far forward as the receiver will allow to increase field of view, while avoiding putting the optic over the barrel nut, which is the hottest part of the carbine. Heat and electronics don't go well together.
Why lower 1/3 co-witness instead of absolute co-witness? I don't want the clutter of having the rear sight in the sight picture. Just too much junk to deal with. I just wanna see the dot and the target. I zero my BUIS and optic separately from each other. Having them all lined up when they're not the same sight system doesn't make much sense to me. Since I run an Aimpoint, the chances of needing my folding Troy Battlesight are very, very slim.
We're in a time when there are better magazines than ever before. USGI aluminum mags get a bad rap, but I'm convinced that happens because there are a whole bunch of magazines still in service that shouldn't be. The latest generation of them has an improved spring and Magpul-like follower, and is a very high quality magazine. However, it costs more than the Magpul PMag does, which seems to beg the question of "why not just buy PMags?" PMags haven't been absolutely perfect and trouble free; there are stories of feed lip problems cropping up here and there, but that may be due to the polymer of different colors being a little problematic. The black NSN PMags have an enviable reputation, and are almost all I use. I have a couple green ones, a few tan ones, and some good aluminum mags from Colt, Okay, BCM, and DSG. The back PMag sees the bulk of the action, though. There are also excellent reports from the Tango Down polymer magazine, too. I know that doesn't narrow things that much, but use this as your guideline: avoid steel mags, they're heavy with no benefit, and in the case of HK, have a short service life. Stick to quality, GOOD CONDITION magazines, whether aluminum or polymer, and GET RID OF THEM when they need to taken out of service. That means destroy them before putting them in the trash bin. Don't bother with mags that aren't in wide distribution. Every now and then, something new comes out, has a huge buzz, and then fades away. Don't bother with being the Johnny Come Lately with magazines. If they're really better, they'll get proven as such over time, and if you need new mags, use them then. Till then, stick with the proven winners. You won't have to drill clearing a double feed as often.
What about stocks? My bro Matt E. put both a Magpul CTR and an LMT SOPMOD on the scale. We always thought the SOPMOD was heavier; its bigger, so it has to be heavier, doesn't it? Turns out it isn't, so it doesn't. They're roughly the same weight. I still like the cheek weld of the SOPMOD and Vltor Modstock, but the CTR is what's on my rifle because I like that it's slim while having some of the characteristics of the cheek weld of the others. One thing I wish it did was to be able to run the sling off the top of the stock as with the Vltor, but that's not necessarily a deal breaker. I don't have a problem with the "LE" style stock that most carbines come with these days, except that it doesn't have a thin pad on it. That pad isn't to tame the thunderous recoil of the 5.56 cartridge, although it probably does aid in that a little. What the pad is for is to keep the buttstock from sliding around in your shoulder pocket. Everybody who's opinion I care about is all about leaning on the rifle aggressively, so the Duostock is a non-starter for me. Probably works great for Camp Perry-type competition, though.
I hate the A2 style pistol grip's finger rest, and I have big hands. I went with the Magpul MIAD to get the fattest grip I could. Most of the quality aftermarket grips have a duckbill or tab that covers the gap between the trigger guard and the grip, and that's a tremendous help if you're shooting 1500 rounds over three days. If you don't have that type of grip, stuff a foam ear plug in there or bust out some tape to keep that finger from being rubbed to the bone.
In terms of slings there's only one design to use: the adjustable two point. Blue Force Gear's Vickers Combat Applications Sling (VCAS) and Viking Tactics VTAC are both excellent. BFG's sling doesn't have a running tail when you adjust it and it's wider. The VTAC adjusts faster but has a running end on the adjusting strap. Both are excellent and both work. Get the padded version if you don't wear armor, and get the non-padded if you do. Padded slings with armor are just extra bulk that you don't get any benefit from.
There are two schools of thought on sling placement: the sling can be close in, using an end plate adapter or sling mount that attaches over the receiver extension and at the receiver end of the rail, or off the stock and at the end of the rail. The advantage to running it in close is that it keeps the sling out of the way of your hands when manipulating the carbine, and generally frees up the carbine to be put into position to be reloaded. Pushing the sling out to the ends lets it hang better on the sling and allows the sling to be used as a tensioning device against the forearm to improve steadiness for longer shots. I find more utility in the sling points being pushed further out.
That sling mount is the ACE 1.5" rail grabber mount.
I like that mount more than any other I've used, because all it does is secure the sling to the rail. The problem with most QD sling mounts is that they end up being bulky, or they're not rotation limited. Daniel Defense mounts are, and I've had good luck with them. I just like the lower profile of the Ace part. It's also only about $20, while most of the QD mounts are around $30, or more. Lots of people cite needing to have a QD to dump the rifle in a hurry if they need to. I guess, but are you training that? I found that the way I'll get the rifle off in a hurry if the need ever arises-and since the chances of me being in an armored vehicle, getting rolled over into a canal in the ME is pretty doggone remote-will be to lift the sling off, like I've always done. If you have a need for a QD, by all means use one. If you don't, save some money and simplify things.
As I said, this is a way, but it comes from those smarter and more experienced than I am. However you set up your carbine, do yourself a favor and use the methods of experienced people. If it doesn't work for you, don't do it, but be honest with yourself and your assessment of "not working".
2 years ago