It seems that fairly often, questions pop up on the forum asking what sort of mods should be made (or what kind of AR rifle should someone get), and typically, the answer is: it depends. The AR family of rifles is pretty versatile, and can be configured for a wide range of roles. From home defense and duty weapons, to competition rifles, to varmint hunting rifles and range plinkers. It helps to have an idea of what sort of rifle you want, before you start spending money on doo-dads that you may, or may not need. Below I have outlined three of the rifles I have built, all of which have slightly different roles.
All of these rifles do share these common traits:
F marked front sight base
DI gas system
A3 style upper
Chrome lined bore & chamber
M-16 style BCG
BCM mod 4 charging handle
Rail section at 10" for mounting a WML
First up (top) is a lightweight urban rifle build. Which I would consider a solid 0-200 yard rifle, good for home defense, really quick to get on targets close in. The upper is a 14.5" BCM BFH mid-length lightweight upper, with a permanently attached Daniel Defense muzzle device to get it to legal length. It has a Larue tactical non-folding BUIS (if you don't need to fold the BUIS down for clearance, why have a folding one?), which I generally like, but would prefer if it had an elevation adjustment. The Aimpoint H-1 2MOA sight is light weight, minimal bulk, quick to acquire, and has a long enough battery life I can leave it turned on for years. Another BCM gunfighter stock, and a PNT trigger help round out the package. This rifle is all about being light and fast on target.
The next (middle) build is what I would consider an all around rifle, or maybe a 3 yard to 400 yard rifle. The upper is a PSA mock dissipator, with a rifle length handguard, but mid length gas system and 16" barrel. It currently has a grip pod on it, but I also usually use this rifle for 3 gun matches, so that gets replaced with a standard VFG. I like the mock dissipator style for the ability to mount things like lights really far out, and get the longest sight radius possible. The Leupold Mark AR 1.5-4x is a touch slower than something like an Aimpoint for really close in, but is a much better choice for close in and really far out. It also has a BCM gunfighter stock (my current favorite for collapsible stocks), and an ALG ACT trigger. This rifle often also has a VTAC sling on it. The Magpul BUIS fits under the scope, out of the way unless I need it. I'm a big fan of this rifle, it is sort of my "jack of all trades" AR, it may not excel in everything an AR can do, but it can do all of those things pretty well.
The final rifle is a 20" build with a fixed stock, something I feel like I don't see a lot of in the civilian world. The length on this rifle makes it less than ideal for clearing houses (although you can do it), but gives me a bit of a velocity and accuracy advantage at longer ranges than a 16" barrel. The upper is another BCM, with a government profile, and rifle length gas system. It also has a grip-pod, for stabilizing from prone/supported positions, and a BCM PNT trigger. I am still toying with the optic on this one, with it currently wearing a Bushnell 1-4x FFP scope. The scope has a lot of solid features on it for the price, and the BDC seems to work well at 4x (although is too small to use as anything other than a dot at 1x), and it illuminates. I am thinking about going with something like a 1-6x Vortex Strike Eagle next, to get a bit more magnification for longer distance. I like the solid feel of a fixed stock, plus it doesn't pull my beard hair out while I shoot, but individuals with smaller statures may have problems shouldering a gun with a fixed stock. This rifle also has an elevation adjustable Matech rear sight, for when I want to shoot adjustable irons. This rifle would be something like a 10-500 yard rifle (depending on target size of course).
So, what kind of purpose built ARs do you have? Did you build them with an intended role in mind?