New Lightweight AR build - recommendations?


March 9, 2013, 09:25 PM
I am planning a new AR .223/5.56 build. Despite current times limiting availability, I'm in no rush and so I just want to spec out what works for me, place orders and wait some time as needed.
So I'm looking for a mid- to high-quality build but I want it to be as lightweight as reasonable. I already have a stripped lower, Geissle trigger, and some other odds and ends but I'm looking for help on the barrel. I'd prefer 14.5" (with brake to make it legal) or 16" but light weight is key. So what brand(s) would you recommend. Budget is not 'sky's the limit' but I don't want to scrimp either. So mid- or somewhat higher is fine. And is 1:8 preferred?
I'm constrained on the stripped upper because it has to be a left-handed build. But what/where can I get one? Stag is so back-ordered that they are not even taking orders at this time.
I was considering a rail-less carbon fiber hand guard. Any other tips?

If you enjoyed reading about "New Lightweight AR build - recommendations?" here in archive, you'll LOVE our community. Come join today for the full version!
March 9, 2013, 09:35 PM
The original design is incredibly light weight. So instead of thinking short barrel, think pencil barrel and start scouting for makers who have them in stock. They usually sell out quick. You can also cruise GB for old uppers to scrounge.

Pencil 20" barrel, floated, with a flat top and light furniture will be a feather as long as you KISS with the accessories.

March 9, 2013, 09:47 PM
skip the flash hider and run a thread protector cap. Get an old Bushmaster BCG with an unshrouded firing pin.

March 10, 2013, 12:21 AM
Is there a reason it has to be a left-handed upper? That really doesn't have much to do with the weight, but is really going to limit your ability to finish this rifle in the next year. The upper, bolt carrier, and bolt are all special on a left-handed rifle, and in my opinion (as a lefty, with plenty of first-hand experience), they are just not worth it.

As far as weight savings go, your biggest moneymaker will be the barrel. I would recommend you look for a 16" lightweight barrel. Even with an A2 flash hider, a 16" barrel is only about 3/4" longer than a 14.5" barrel with a pinned muzzle device. The weight savings of a pinned 14.5" is going to be negligible, if it exists at all. To me, that gives the advantage to the 16" barrel, because you won't be stuck with a semi-permanent set up.

Concerning handguards and anything else, everything depends on your definition of "lightweight as reasonable", and your intended use of the rifle. On one extreme, you could draw the "reasonable" line at dimpling a LW barrel, drilling speed holes in things, or leaving out parts. Another definition of "reasonable" might be using parts that are readily available and can be assembled at your kitchen table. Regarding your intended use, there are things that can be done to lighten a rifle that I would never do to a lightweight defensive carbine.

Everything in this discussion is relative, and we will be able to provide you with better feedback if you give us some more parameters to work inside of.

March 10, 2013, 01:36 AM
When it comes to real light weight build I think one needs to first decide if he or she is willing to sacrifice function or reliability/durability and how much. I suppose this is what you may have meant by reasonable, but as mentioned above by Mr.Clean what is "reasonable" varies considerably depending on who you ask.

I know you said you want a 14.5 or 16" gun but if you truly want a light weight gun an SBR is the way to go. A 10.5 gun is notably lighter than an otherwise identical 16" gun.

Another thing that will save a pretty notable amount of weight is the use of a cav arms lower. It is about a full pound less than a complete forged lower with A2 grip and CAR stock.

Barring those two things the next best way to get a lighter guns is to go with a lightweight (AKA pencil) barrel. A 14.5" with a pinned muzzle device will save a bit of weight over a 16" gun at the cost of having a pinned muzzle device.

As to twist rate it depends on the weight of bullets you want to use. I like 1:7s, but some really good guns like those from LaRue use 1:8

There are lots of steps that can be taken to shave weight, including things like lightweight BCGs, etc, etc. Just depends on how crazy you want to get with the lightweight theme.

March 10, 2013, 02:34 PM
Subscribing... I just got a polymer NF lower to go with a flattop PSA upper I have. I plan on putting in a mil-spec LPK, pencil 16" barrel, and CAR type buttstock unless someone can recommend a lighter one. Are free-floated forends necessarily heavier than the standard ones? I imagine the hardware near the receiver adds some weight to free float, right?

March 10, 2013, 03:24 PM
Are free-floated forends necessarily heavier than the standard ones?

They are not per se heavier. In fact some of the lightest setups are going to be some of the carbon fiber tubes. Some attach in ways that weigh less than the delta ring etc on regular hand guards.

March 10, 2013, 03:28 PM
Take a look at BCM's website. They have 14.5" midlength pencil barrels in stock right now.

March 10, 2013, 05:54 PM
I agree with Cosmoline. The AR is already a super light gun in its normal design. You don't have to work at it to have a light weight gun.

That said, I'd go with Magpul furniture. Very light weight. Light on the wallet, too! You can get a highly functional Magpul handguard for around $35 - $40.

March 10, 2013, 08:20 PM
Must you have a left handed upper? A righty AR15 upper with a shell deflector and properly tuned extractor is nearly as good and gives you many more options.

March 10, 2013, 09:08 PM
1:7 for me as i want to hunt with the 70grain GMX bullet. Pencil profile barrel of the length you desire. 16" mid length for me.

April 1, 2013, 01:56 AM
Yes I strongly prefer a LH design. It will match another AR 5.56 and AR-style in .22LR.
Edit: Let me expand on my comments. As noted, I strongly prefer a LH design. I have another AR .223 that is LH, an AR in .22LR that is LH and a Tikka bolt action in .308 that is LH. I also accept, painful though it may be that this will delay and/or increase cost of the project. I'm OK with going slow. In fact I started accumulating parts two years ago with the intent that I'd do this some day but never got around to it.
For whatever the reason, this seems like a good time. So I purchased a DD 14.5 lightweight barrel (BTW, had I heard this feedback before ordering, I would have purchased the 16" one with a permanent thread cover - if I could stand the look), a stripped upper (LH), a stripped lower, and a LPK. All but the barrel were purchased two years back with the barrel being a recent purchase. Clearly the big hurdle is the BCG in LH. I saw a Stag one advertised on one of these forums but the guy wants $300 which is just incredibly high and I'll have to delay the project much longer if that is representative of the going rate for average BCG's.
Regarding the use, ahhh, I don't know. It's likely plinking, some 200 paper punching and some day maybe I'll take it hunting. I will say that when I first received my Stag LH 3G, I was impressed by everything except for it's weight and it's weight distribution. It just seems unnecessarily nose heavy and so it's not a joy to carry. So I'm looking for a reasonable quality build that will have a different set of tradeoffs to compliment the 3G.

April 1, 2013, 06:54 AM
I've got a Daniel Defense 16" midlength lightweight barrel on my build. The barrel is pencil profile, 1:7 and IIRC chrome lined. Shoots great and the entire gun is a hair under 6# with iron sights.

April 2, 2013, 01:01 AM
I agree with Cosmoline. The AR is already a super light gun in its normal design. You don't have to work at it to have a light weight gun.perhaps, but if you're not careful it can get really heavy really quick.

April 2, 2013, 12:30 PM
MAG tactical lowers are as light as you get without going plastic. A pencil barrel, a carbon fiber FF tube; should be able to build a rifle that comes in under 6 lbs no problem.

April 2, 2013, 12:58 PM
Not a solution for you (already have lower and need LH) but Colt's new non-mil-spec 6900 light rifle comes in almost a pound lighter than the mil-spec 6920 despite having standard taper barrel. I have one and I'm loving it. Excellent single-stage match trigger too. Putting a light barrel on it would be even lighter.


April 2, 2013, 01:22 PM
If you didn't already have the lower I would second Girodins Cav Arms lower suggestion. I have a factory rifle from Sabre Defence that uses this lower specifically. It's named the "Light Sabre". Seems fairly well built and it is roughly 1lb lighter than a similar build with a metal lower and tube.

If you enjoyed reading about "New Lightweight AR build - recommendations?" here in archive, you'll LOVE our community. Come join today for the full version!