Update April 2018: Wow, this post is nearly five years old and in that time the concept outlined here has more than become reality! Five years ago we weren’t swimming in sub-10oz free float rails, lightweight components, minimalist optic mounts and more. At this point it’s foolhardy to skimp on the nickel boron bolt group, and as of the time of this update one can procure a lightened NiB group from AIM for all of $99, a product which five years ago would’ve cost you $300+ from a boutique manufacturer. Progress is a wonderful thing sometimes, huh? I’ve made some changes below to reflect the changing times.
I was talking to a friend and customer of mine recently about putting together a light weight AR-15 that also has the features people really want in a good rifle. Typically the first thing is a chrome lined barrel, followed by replacing the rattle trap M4 stock and chintzy A2 pistol grip. I thought about it a bit and decided on what I would consider a personal baseline for a quality lightweight carbine.
Let’s set up a couple of definitions first, to clarify what I mean:
- “Production” means an affordable, relatively quick to assemble rifle with available parts. This means no fancy custom components like JP bolt groups
, though a Nickel Boron option or free float handguards could be doable.
- “Lightweight” means a pencil profile barrel and components selected for maximum weight savings. The overall unloaded weight with magazine should fall somewhere between 5.5-6.5 pounds but if possible the lighter the better!
Why a lightweight rifle specifically?
A lightweight carbine has a lot of possible applications ranging from home defense or ranch rifle use to breaking the gun down for backpack transport. For the latter, many people decide against a long gun for backpack trips due to the fact your average AR-15 weighs several times as much as a good magnum caliber pistol in a situation where ounces become pounds. For the former, not everyone buys into the idea that they should be loaded down with a Redi-Mag, variable power optic with offset RMR and an expensive aluminum railed handguard on their gun.
The modern tactical mindset has kind of pushed people into two divergent crowds: the ready for everything folks who spare no expense on accessories and the “KISS” group who usually just buy a bone stock off the shelf brand name rifle and call it good. We’re here to think outside the box a little and explore the gap between them, where we still have a straightforward rifle but equipped with absolutely useful upgrades for a reasonable price.
What’s the baseline?
Here is what I’ve come up with for a kind of baseline carbine, no frills but adaptable to a light mount and of course optics; I consider both of these must-have items on a defense gun of any kind.
- 16″ Chrome Lined barrel, Pencil profile, Midlength gas, 1:7 or 1:8 twist  Melonite is also a good alternative and has proven its worth since the original writing!
- Standard phosphate bolt group, Nickel Boron optional and recommended  Honestly NiB is mandatory for me now, and a lightweight NiB preferable for similar pricing now.
- Slick-side T-marked, M4 feed ramp upper (alt: 9mm upper with gas tube hole drilled)
- Lightweight lower receiver e.g. TN Arms polymer hybrid
Magpul MOE handguards Find any lightweight rail, for 15″ length sub-9oz and for shorter of course lighter approx 1oz per inch of rail
- Any grip of your choice, I prefer Magpul or Hogue
- Magpul CTR or BattleLink Minimalist stock
- Your choice of sling, minimalist mount using forward swivel and a rear paracord loop  These days we’d probably just use an M-LOK point for this.
This setup is easily adapted to an “Optics Ready” build
using a low profile gas block (even less weight!) and could certainly be made to order with free float rails for a price. The rifle as described would weigh in at about 6 pounds with magazine, possibly lighter depending on choice of lower and gas block. My preferred setup here would be a Midwest Industries lightweight M-LOK or KeyMod 12″ rail, or 15″ if you want to trade an ounce or so for a longer BUIS sight radius.
I’m sure anyone reading this far is wondering why I would opt for a standard bolt group and upper. The reason is basically cost effectiveness, and that the nickel boron BCG would be an easily added option for under $180. While a JP low mass BCG would be an excellent addition, the carrier alone costs $225. Thanks to more companies offering slickside uppers with no forward assist (which is by and large a useless feature) there’s not much cost difference to go with one for a build. Aero Precision is my go-to for a slickside upper, currently retailing at $85. Remember, this is a baseline to work from!  Nowadays NiB BCGs retail for under $99, with lightweight carriers slightly more. The times, they are a changin’!
Estimated retail cost: $750-1000 built to order
I wanted to put the idea out there for anyone who might be interested. After checking around it seems there are essentially no factory produced guns set up this way, and the closest thing in quality and features starts at over $1000!  Hey at least one thing didn’t change, the race for the lightest AR made these things cost a ton. I can still make them for a grand out the door instead!