What is considered to be a lightweight AR?

[BSA1]

What is considered to be a lightweight AR?

Short story is I finished building my first AR last month. It is what I consider to be a typical AR rifle with 16” barrel. I am hoping it will be a very accurate range gun.

For my next AR I want to build a lightweight AR. I am using a Anderson Lower as I have several on hand, Anderson slick side upper (no forward assist, brass defector and ejection port cover) and a 14.5” barrel with permanently attached flash hider (no NFA SBR). I will build most of the rifle myself and using the weight of parts listed by the manufacturer I am pushing seven pounds. At the moment I have choose Magpul stock, grip and forearm.

My budget is $1,000. The msrp for parts on my first gun was $907.00 and my actual cost was only $675.00 as I caught some good sales.

The barrel is the most obvious place to reduce weight. Which is lighter; fluted or pencil contour barrel? Loss of accuracy due to barrel heating up is not a concern.

Any other parts to look at for reducing weight?

 

[crazysccrmd]

http://68forums.com/forums/showthread.php?49304-New-Project-light-weight-4-89-pound-6-8-SPC-II

The guy who started this thread builds super lightweight AR15s and AR10s. I don't think you'll be able to get down to 3.25lbs like he did and stay within your budget but it will still show you a lot of options and methods to keep the weight down.

 

[LoonWulf]

Sources parts and spend wisely you can probably get under 5 pretty affordably. My lightweight build still uses the same lower as my 458 so its not really that light, it comes in just under 8 scoped with a heavy scope.



Oops ment under 6

 

[Varminterror]

I tend to consider anything under 8lbs, scoped, to be a lightweight AR. Guys can go a LOT lighter than this, but they're usually spending a LOT of money to do so. By "under 8lbs," give it at least a pound of weight loss, so 7-ish pounds is light for an AR. Get down under 6lbs and you're spending a lot of money to get super light, or hyperlight.

Why pick 8lbs? Well... If you "don't try to build light, but try not to build heavy," and build a standard weight AR, you'll usually end up with about 8lbs for a carbine to 18" rifle. Anything markedly lighter is a "lightweight."

For example - this one I built on a standard weight 18" barrel, relatively light P223 mount and a standard weight Bushnell AR 3-9x40mm optic. The CTR stock is relatively light, the Nordic forend is remarkably light, gas block is steel and a bit bulky, standard forged upper & lower... It comes in at 8lbs 9.6oz without a magazine.

Slick down the side of the upper to eliminate a few ounces of port cover, deflector, and forward assist, knock down the barrel weight a bit with fluting or pencil weight, drop to a lighter gas block, cut down to a 16" tube, eliminate the muzzle break, and commit to a lighter scope, a guy can knock a pound to pound and a half off of this rig pretty easily and get down to about 7lbs. There are lighter stocks and lighter handguards out there, but not many. The barrel profile is the easiest way to draw down the most weight, since that's a big volume of heavy steel. I spent $40 on that handguard, I could have saved a little weight by using a $240 Lancer carbon fiber handguard...

Grab a slick side upper, a CTR stock, a pencil weight barrel with no muzzle device, a nordic handguard, low profile, set screw mount, non-adjustable gas block, P223 rings, and a lighter weight 1-4x scope or iron sights and you'll find yourself in the 6.5-7lb ballpark.

 

[primalmu]

I agree with Varminterror -- I don't consider anything much less than 7 lbs to be all that practical. I build a "lightweight" rifle that weighs about 7.25 lbs with empty aluminum mag and Vortex StrikeFire. Parts include:

• Delton 16" pencil barrel - $150
• Magpul MOE carbine handguard w/ VFG - $20 (sale)
• Aero Precision lightweight upper - $40
• Aero Precision lower - $50
• MFT Minimalist stock - $50
• UTG Flip-up rear sight - $20

Including miscellaneous parts, it probably cost me right around $500 +/- $50, not including the Vortex StrikeFire optic. I had quite a number of spare parts that I put together for the build, so I'm not sure of the exact cost. I think that's probably about as good as you can get for $500, though, and holding it I can't imagine needing anything lighter. With the pencil barrel, the center of mass is more to the rear which really helps the rifle "feel" lighter.

 

[R.W.Dale]

I am running a poly lower, no buffer (taccom) and an aluminum bolt carrier to get a 300blk under 6lbs


http://i3.photobucket.com/albums/y96/krochus/E8CE73B7-6790-4E1E-9D66-872FB0A3A2F5_zpsudhjhkgb.jpg

 

[Varminterror]

Oh - I forgot to add in my post - the total price for the 18" carbine in my post above, including 5x 30rnd mags and the optic, was $1,100 shipped to the customer, including load development. Polished Rock River Nat'l Match 2 stage with hand tuned JP reduced springs, Black Hole Weaponry barrel. He skimped on the optics, planning to add a Vortex at a later date, but he's sent me pictures with the rifle and coyotes it has killed from 400-600yrds.

 

[Jackal]

I consider a lightweight to be about 6lbs or less. 16" pencil barrel, a 10oz ish free float, forged upper/lower and a MFT stock. Pretty much that easy.

 

[chicharrones]

I consider an AR lightweight if its near 6 lbs., as well.

ARs in the 7 to 8 lbs. range are what I consider normal if with optics. ARs hitting 9 lbs. and more are what I consider heavy, for a 5.56 AR.

 

[BSA1]

Thanks for the comments so far.

LoonWolf,
How about specific part suggestions? All of the under 5 pound AR’s I have looked at on the Internet are pretty radical and expensive.

Varminterror and primalmu I will take a look at your parts suggestions.

No poly lower.

It does sounds like I am pretty much on target at 7 pounds.

 

[Jackal]

A Faxon pencil barrel and gas block, 12" Midwest or BCM rail, Daniel Defense sights and a MFT stock will get you in the 5.5lb range without breaking a sweat (or the bank). Start adding fancy lightweight receivers, titanium small parts, lightweight bcg's, titanium muzzle device, titanium barrel nut, etc and your cost starts to go waaaay up. It costs roughly double to go from a 5.5lb down to a 4.5lb rifle.

Also, optics are an area that holds a lot of hidden weight. My Aero Precision extended mount AND my Leupold 1.5-4x scope weigh a combined 12.5 oz. Compare that to a Vortex Strike Eagle (less clear, more expensive, worse eye relief and worse eyebox than the Leupy) at 17.5oz without mount.

 

[1stmarine]

If a gust of wind will blow it away, you have gone too far.

For me, as for millions of other people, a 6-8lb carbine is a light firearm.

Light weight is also relative because what is heavy for you might be light for me or vice-versa.
I think when taking things to extremes, one needs to consider also what kind of compromises one is willing to accept.
There is never a free ride with physics. If you take from some place you pay for it somewhere else.

IMO, the standard parts AR with a medium profile 16"-18" barrel is a pretty light and handy firearm already.
Same thing with the average 16" AKM.

 

[TJx]

I'm at 6.2 lbs with this without trying hard except wanting to put a lightweight barrel on it. The rail was a practical choice since I didn't see a need for the full length Picatinny.
The lower is a stock Colt LE6920 except for butt stock (MOE SL) and Geissele SSA trigger
Barrel is a 16" Ballistic Advantage Hanson mid-length listed at 22 ounces.
Rail: ALG Ergonomic Modular 12” Rail (EMR) V2 M-LOK
Front sight DD
Rear Sight Magpul MBUS Pro
Standard Aero upper
Flash suppressor: Smith Enterprise G6-A4 Vortex
Charging handle: Gunfighter Mod 4 Ambidextrous

 

[R.W.Dale]

Your biggest weight savers over just slapping a pencil bbl on a standard AR will be a Taccom buffer and a whiskey Arms Aluminum bolt carrier.

These two parts together are the best part of a pound but will require an adjustable gas block.

The second biggest weight saver will be a cav Arms lower. Not because it's plastic so much as it eliminates a buffer tube, nut, pistol grip and bolt. This is the only poly lower I trust to not break because its monolithic and doesn't rely on threads in plastic. But the weight saving here is minor compared to the two parts above.

Even with a bbl not quite as light as it could be this puts me at 5.8lbs with a 10rd p mag and a 2-7 compact leupold scope. No other exotic parts and a full weight castle nut delta ring with handguards

 

[1stmarine]

For a light duty carbine might be fine but is the weight difference really worth to trade off?
Those are the precise parts I would never mess up with that are the beating heart of the AR.

 

[R.W.Dale]

For a light duty carbine might be fine but is the weight difference really worth to trade off?
Those are the precise parts I would never mess up with that are the beating heart of the AR.

For a fun / hunting gun if it will go bang two times in a row with reasonable reliability it's good enough.

But in the case of mine once the gas is adjusted for the load it's been rock solid. IMO you should not be relying on a gun you assembled from pieces on sale for anything life or death.

What I learned from my build is it's actually really hard to build an Ar that won't run

 

[mjsdwash]

you can buy a DTI lightweight midlength kit at 5.8 lbs with a carry handle. I had a kit with an a2 handle, 6 position stock, and a bushmaster pencil barrel that weighed 5.5 lbs. At 5.5 it feels like a toy, but still has aluminum receivers, and a decent quality barrel and stock. that guy has about 14 thousand rounds through it, and is well beat up, but still runs. I think to get below 5lb you need to put plastic in places it shouldent go. Both of those rifles cost 600$ roughly, and a pencil will weigh far less than a fluted heavy. No parts breaks, and it usually runs about 1-200 hundred rounds a session, in addition to maybe 5000 rounds through a 22 conversion. I wipe it down with oil after each cold weather use to prevent rust, but have only cleaned it twice. It never got dirty enough to jam, and accuracy only opened up once early on, that was the first cleaning. The last time I looked through it, the barrel extension had what looked like wool filling the space. Mostly 22lr lead/wax, regular carbon, and oil. I felt I should probably clean that. I would not go lightweight on anything in the bolt group. But you can defenetly get a reliable AND durable 16" metal AR below 6lb, and well under $1000. That is with a2 sights though.

 

[1stmarine]

For a fun / hunting gun if it will go bang two times in a row with reasonable reliability it's good enough.
But in the case of mine once the gas is adjusted for the load it's been rock solid. IMO you should not be relying on a gun you assembled from pieces on sale for anything life or death.
What I learned from my build is it's actually really hard to build an Ar that won't run

I understand.
As soon as one stays away from the M4 style & el cheapo kits and uses quality parts the chance to build one that will not run reliably are minimized.
A quality bolt is also paramount.

 

[R.W.Dale]

I understand.
As soon as one stays away from the M4 style & el cheapo kits and uses quality parts the chance to build one that will not run reliably are minimized.
A quality bolt is also paramount.

The lightweight alternative material BCG components are very high quality because by in large they're being developed for competition to reduce cycling time. Being lightweight just happens to be a bonus.

An aluminum carrier is a wear item however. Most competitive shooters report wearing one out a season. But in terms of a lightweight hiking rifle for hill country that's a few lifetimes of shooting.

I'm coming to the conclusion that the buffer is a completely unnecessary part once you have the ability to control the gas you're sending down the tube.

 

[1stmarine]

The lightweight alternative material BCG components are very high quality because by in large they're being developed for competition to reduce cycling time. Being lightweight just happens to be a bonus.

An aluminum carrier is a wear item however. Most competitive shooters report wearing one out a season. But in terms of a lightweight hiking rifle for hill country that's a few lifetimes of shooting.

I'm coming to the conclusion that the buffer is a completely unnecessary part once you have the ability to control the gas you're sending down the tube.

Makes sense for that kind of role/purpose.

I see a lot of new "inventions" for light packing carbines when in fact one could have a super light AR that breaks down naturally and goes inside a backpack like nothing.
Will also take 22LR ammo with a simple add-on. So here is a super popular modular system w/o the need to reinvent the wheel in the year 2016.

I think the main purpose to increase a tad buffer weight is to make a critical duty carbine that will reliably run with standard parts and any kind of ammo in any conditions from
the hot desert to the arctic.
Also by slowing down the group we drastically increase the reliability that it becomes more critical in sustain fire or bursts. It doesn't have to be a heavy piston AR
although I would stay away from M4 style barrel cuts, carbine porting and 1/2" threads that serve no purpose at all and might be the source of headaches. All design mistakes
that should have never been gone mainstream. Never understood why the M4 style barrels became popular in civilian market.
One misconception is that when the AR is submitted to the hardest tests like continuous suppressing fire is that the gas tube and bolt will fail but this is not true and other things
might fail prematurely as a result of the M4's poor design.

Luckily we have unparalleled aftermarket and great alternatives even for a standard more robust AR w/o increasing weight over the service carbine. Or at least increasing in
any significant and noticeable way in practical terms.

With the pencil barrels I am always concerned about some of the minor diameters in critical areas ahead of the chamber. IMO some have gone too far and this also includes
some wider profiles with deep and/or fancy fluting. Another thing that doesn't make a lot of sense. I am not judging cosmetics, just from the engineering stand point.

I am not saying all pencil barrels are bad, but how much 6" of a .60 vs .75 profile saves at the end of the day. Or when minor diameter in deep fluting goes as deep as .50 right in front of the gas block in a carbine.

 

[PowerG]

I saw a video where Colt fired a light barrel M4 full auto to failure, changing magazines as fast as they could. The barrel drooped and then ruptured at 535 rounds. IIRC it took them about two minutes to fire that many rounds. (Edit: found it. The second video is of a normal M4 barrel, when I saw these they were two separate videos.)

 

[primalmu]

I saw a video where Colt fired a light barrel M4 full auto to failure, changing magazines as fast as they could. The barrel drooped and then ruptured at 535 rounds. IIRC it took them about two minutes to fire that many rounds.

I don't think it is a pencil barrel, but this one took 830 rounds:

 

[1stmarine]

Thanks for finding those videos and sharing.
Even well before the point of failure those barrels were trashed on this critical section.
The M4 cuts make little sense even for the military. I would have been wiser to keep a mid length and
redesign the M203 bracket and even the grenade launcher from scratch vs compromising
the design of the service carbine. also keep 5/8 threads at the muzzle.
What I don't get is why people buy M4 style barrels and other fancy cuts for their ARs.
I cannot think of one single reasonable explanation. I know most people will not plan to ever use an AR for
suppressing fire but still.. a better more robust design doesn't have to be bulk nor heavy.

 

[Jackal]

I never have seen the purpose for a 10lb AR15. My 6.5lb Larue barrelled carbine puts bullets where I want them out to 500m.

Colt fired a light barrel M4 full auto to failure, changing magazines as fast as they could. The barrel drooped and then ruptured at 535 rounds.

535 rounds is pretty darn impressive. I havnt even fired 500rds through my lightweight yet in over a year. Then again, my lightweight is as accurate as many folks bull barrels.

 

[hdwhit]

Any other parts to look at for reducing weight?

The receiver. Skip the aluminum lowers and go for polymer.

The barrel. Use a so-called "pencil" profile.

The stock. Use a skeletonized stock.

Handguards. Use a carbine-length gas system and handguards without a heat shield.

Eliminate the dust cover over the bolt carrier.

Also, use a gas block without an integral front sight and instead use a red-dot sight.