Lightest 16" 5.56NATO AR-15:

[mshootnit]

I like light barrels myself especially in the larger calibers, but I do see the value in having the additional barrel material acting as a heat sink in case you ever need to fire off a bunch of rounds quickly, sustained fire.

 

[vkeith]

I'll be following this thread since I've started collecting parts for a budget conscious lightweight build.

I chose the Faxon 14.5" pencil barrel with integrated flash hider because it is the lightest steel barrel at just over 19 ounces bare and is reasonably priced when on sale.

OP, AR15.com has a couple of long running threads on lightweight builds and lightweight parts that should be very helpful to you.

 

[Charlie98]

I like light barrels myself especially in the larger calibers, but I do see the value in having the additional barrel material acting as a heat sink in case you ever need to fire off a bunch of rounds quickly, sustained fire.

I've gotten away from the very light barrels in the AR meself. I've got a lightweight barrel on one of my carbines, and if I run 3 magazines through it in normal shooting drills, the (arguably poorly designed) Magpul forearm gets so frikking hot, I have to put a glove on to shoot. I built my brother a basically identical upper last month, with a heavier barrel, and while it still gets hot, it takes about twice as long to get to the glove stage. Granted... everything has it's place, and if you are looking for light weight, that's the solution.

 

[Phaedrus/69]

This is a fascinating thread! My favorite "AR" is my PWS Mk114 Composite gun (Mod 1 upper/Mod 2 lower). It shoots great and it's just all around awesome. BUT...my buddy has a very basic Colt with a pencil barrel, shorty handguard, etc. that makes my PWS feel like a boat anchor. I don't really have to hump mine all over creation so weight isn't that big a deal but I can see the appeal of very light carbine stripped down to just what it needs with nothing it doesn't.

 

[Maverick223]

What magazines/capacity are you considering?
Any thoughts to some hybrid, poly ammo?
Moon

I have a strong preference for 20rnd lancer L5s, but I have a lot to choose from including some 5, 10, 20, 30, and larger capacity, some made from carbon fiber but most are aluminum, polymer (some reinforced, some aren't), & steel (which are unlikely to be used here). Honestly 20rnd aluminum are probably the best choice here, so that's what I'll probably end up using. As far as polymer cased ammo, I really liked what I saw from TrueVelocity at SHOT show a couple years ago (I really think they and General Dynamics had the best combo for the NGWS entry, but that's a different story), but until prices come down on that stuff I'm probably going to be rocking brass M193 (my standard fodder) or some 45gr HP instead. $2/rnd it's pretty crazy if you ask me!

My last build from the ground up was with a pencil barrel, and that's my strong preference now a days.

My current build only has a gov't profile because I got such a good deal on it and don't want to fiddle with getting another barrel drilled and pinned for a FSB. The government profile is weird, I'd prefer the extra meat by the chamber rather than the muzzle, but at least it's not overly heavy.

I agree, I have several pencil barrels and they're a great option when you're not looking for sustained fire capability. There were other factors (like attachments) at play when the Govt. profile was chosen, most of these are not a factor for us, so arguably there are much better choices in most cases.

If I had a nickel every time a customer said "lightweight AR build" I'd have a couple hundred $$$.
I would have another couple of hundred $$$ for every customer that wound up abandoning the concept.

You may be correct, but we're going to give it a go...I'm pretty stubborn if nothing else. I'm betting I can pull it off given what I'm after and my expectations (keeping in mind this is never intended to be practical, much less a "go-to carbine").

I'll be following this thread since I've started collecting parts for a budget conscious lightweight build.

I chose the Faxon 14.5" pencil barrel with integrated flash hider because it is the lightest steel barrel at just over 19 ounces bare and is reasonably priced when on sale.

OP, AR15.com has a couple of long running threads on lightweight builds and lightweight parts that should be very helpful to you.

If you're talking about the 16"OAL bbl that's the exact one I chose. I have a couple other Faxon bbls (both pencils: one a 16" forged 5.56NATO, the other a 14.5" .223Wylde) and they've performed well at a reasonable price whilst saving a bit of weight. Thank you for the reference; I'll have to check out some of those threads.

 

[WestKentucky]

I kept an eye towards light but functional with the cheapo I just ordered parts for. It’s going to be a pig, but it’s not going to be my 22” doublestar 1” heavy profile 6.8 barrel rifle either. The 6.8 is a mixmaster of sorts and all were aimed at cost effective accuracy. The complete upper was a used upper bought off of a militaria type secondhand store with consignment gun shop wall. Cool place.

The lightest functional carbine I have ever seen was pretty horrible. The handguard was significantly hacked up, there was essentially a suction cup used as a stock, and the upper and lower were excessively milled. No titanium that I know of in that one but I know that it flexed a lot when firing.

 

[Professor Gascan]

With the use of the AR parts weight database from arfcom, I built mine with a reasonable budget and expectations and came out at 5lbs 1 oz with a red dot and no backup sights without using anything too exotic or expensive.

If no one mentioned it before it's an invaluable research tool to see for yourself witch parts are worth it to you in the weight/price ratio...

 

[Maverick223]

Apologies for the radio silence as of late...it's been back to the grindstone, so I haven't had much time for development updates. In the meantime all parts worth the exception of the red dot (should arrive today) and barrel (still backordered until next month) have arrived and been installed where possible (obviously no gas system components due to the lack of barrel). I'll try to get a photo up this evening with the sight installed.

P.S.: I still haven't made a decision on the bolt hold open. I'm thinking that I may just wait to completion to see where I'm at and decide if the couple of grams savings using a titanium part is worth the cost over my skeletonized one.

 

[DustyGmt]

I suspect you'll reach the same conclusion many of us did after engaging this pursuit and building sub-4 or even sub-3 pound guns. That is, too many sacrifices are made.

It's pretty easy to build a durable & reliable ~5 lb AR.

It's much more difficult and expensive at 4 lbs.

At 3 lbs, you have a very specialized and fragile thing.

I've also made from scratch some of the lightest repeating rifles you can imagine, including a 5-shot bolt action .22 that weighs only 19 ounces, so I get it, but again, some of the compromises/sacrifices that have to be made to get there are not trivial. My 3.2 pound folding 9mm semiautomatic rifle actually worked out pretty well, but the bolt is so light that it's borderline on not blowing cases out, and it's not even worth suppressing with such early breech opening and high bolt speed, have 151 decibels at shooter's ear from port noise.

Have you ever contributed any pics or threads on these builds? Sounds very cool

 

[MachIVshooter]

Have you ever contributed any pics or threads on these builds? Sounds very cool

A long time ago, probably somewhere in the archives. It was 8 or 10 years ago the last time I did a light weight build, and they wouldn't be very helpful to anyone who isn't a machinist, as most of the parts were either modified or completely custom. One-off aluminum receiver extension nut, titanium selector, skeletonized billet aluminum RMR mount, pinned titanium muzzle brake, then upper receivers, handguards and bolt carriers put on a diet on the knee mill, 14.5" barrel turned to sub-pencil profile, etc.

 

[adcoch1]

A long time ago, probably somewhere in the archives. It was 8 or 10 years ago the last time I did a light weight build, and they wouldn't be very helpful to anyone who isn't a machinist, as most of the parts were either modified or completely custom. One-off aluminum receiver extension nut, titanium selector, skeletonized billet aluminum RMR mount, pinned titanium muzzle brake, then upper receivers, handguards and bolt carriers put on a diet on the knee mill, 14.5" barrel turned to sub-pencil profile, etc.

I remember seeing some of that. Inspired me to try some stuff with my old lathe. Good stuff. And a lot of good ideas.

 

[hq]

with a heavier barrel, and while it still gets hot, it takes about twice as long to get to the glove stage.

Remember that the heat issue works both ways. A light barrel also cools much faster, so if you're having a long range session, it evens out in shorter cooling breaks. Personally I'm fond of heat shields inside the handguard, either milspec or silica-based, 650°C/1200°F rated Aerogel-type insulation material on the inside of float tube.

With full auto a heavy barrel is a must. It's incredibly easy to fry a pencil barrel with just a few magazines and once it starts to glow red, you know damage has been done.

I rarely shoot extended sessions anymore and haven't competed in several years, but I still have a box full of scorched and melt handguards in the basement reminding me of what may happen.

 

[Phaedrus/69]

Until ammo prices come down I'm in no danger of melting down any barrels!

 

[DustyGmt]

A long time ago, probably somewhere in the archives. It was 8 or 10 years ago the last time I did a light weight build, and they wouldn't be very helpful to anyone who isn't a machinist, as most of the parts were either modified or completely custom. One-off aluminum receiver extension nut, titanium selector, skeletonized billet aluminum RMR mount, pinned titanium muzzle brake, then upper receivers, handguards and bolt carriers put on a diet on the knee mill, 14.5" barrel turned to sub-pencil profile, etc.

Nice, I was actually referring to your 5 shot .22lr and the 3# 9mm semi home builds....

 

[MachIVshooter]

Nice, I was actually referring to your 5 shot .22lr and the 3# 9mm semi home builds....

I won't derail this thread by going into details about those two, but here are links. Lots of photos are missing, as they were photobucket hosted before the outfit went full retard. Same story with YouTube, I deleted that account. We use Juxxi (full30) now, but I have not and don't plan to find and re-upload the videos of these builds for a variety of reasons.

Anyway:

https://www.thehighroad.org/index.p...ogress-lightest-one-yet.814601/#post-10428656


https://www.thehighroad.org/index.php?threads/ultralight-folding-9mm-pack-rifle-begins.811763/

 

[InTheSwamp]

The lightest AR-15 rifle is the one you build only to realize is too light for your intended purpose. Old-Timers went to war with Mausers and Garands, and never b* about the weight.
Couple extra ounces here and there don't hurt, as long as performance is achieved.