What is considered to be a lightweight AR?

[Speedo66]

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.

Unfortunately, most kits, etc. seem to come standard with the M4 profile. I would have preferred a lightweight barrel, but all the sale deals at the time included the M4 profile.

I guess the companies all feel everyone wants to play army.

 

[BSA1]

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

er…No
I will gladly live with a few more ounces for a critical part that will last a lifetime than a breakable part that will leave the gun useless. Beside I already have Anderson Lowers.

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

What is a fluted barrel and the differences between it and a pencil barrel?

3. The stock. Use a skeletonized stock.

Suggestions?

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

I had not thought of that. I do like the looks of the Magpul SL handguard.

5. Eliminate the dust cover over the bolt carrier.

Check. I am probably going to use Anderson slick side receiver with no forward assist, brass defector and ejection port cover.

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

Check. It is the only way I can d-i-y with a 14.5” with a permanently attached flash hider

 

[GAF]

1 2 3

 

[MachIVshooter]

Under 6 lbs. without magazine or optics is a lightweight, and not difficult to accomplish for reasonable cost. Under 6 with loaded 30 round mag and optics is ultralight, and if you can't modify and manufacture parts yourself, it'll get spendy.

 

[R.W.Dale]

There are polymer lowers and there are polymer lowers.

Poly conventional lowers are by in large garbage and save next to no weight

The cav15 monolithic lower saves a bunch of weight because it eleminates a bunch of parts and lacks the failure point all other polymer lowers have. The buffer tube hoop.

But you don't get to play with a weighty collapsible buttstock

 

[R.W.Dale]

Under 6 lbs. without magazine or optics is a lightweight, and not difficult to accomplish for reasonable cost. Under 6 with loaded 30 round mag and optics is ultralight, and if you can't modify and manufacture parts yourself, it'll get spendy.

Not necessarily

You just have to take the big savers. I.e. Aluminum carrier and lightweight buffer.

My build list
Ar15 build

Lower $120
Trigger pins $6
Vise blocks $15
Mystery bbl $134
Carbine handgaurds $29
Charging handle $15
LPK $35
Bolt carrier $206
Upper $45
Buffer $30
Bolt $30

ETA I missed the loaded 30 RD mag.

But honestly who builds an ultralight to burn through mags for fun.

 

[chicharrones]

ETA I missed the loaded 30 RD mag.

But honestly who builds an ultralight to burn through mags for fun.

That's a good point. I'd think an ultralight would be better with a 20 round mag at most.

 

[BSA1]

While I already have 30 round mags on hand for this gun I plan on using 20 rounds mags. Actually I like 20 round ones better than 30 anyway.

Thanks for some good suggestions and staying on topic.

 

[MachIVshooter]

Not necessarily

You just have to take the big savers. I.e. Aluminum carrier and lightweight buffer.

My build list
Ar15 build

Lower $120
Trigger pins $6
Vise blocks $15
Mystery bbl $134
Carbine handgaurds $29
Charging handle $15
LPK $35
Bolt carrier $206
Upper $45
Buffer $30
Bolt $30

ETA I missed the loaded 30 RD mag.

But honestly who builds an ultralight to burn through mags for fun.

Left out a few things there (gas block, gas tube, barrel nut assembly, muzzle device), and I'd like to know where you are getting $35 LPKs, unless they don't include fire control parts, in which case you forgot to add those as well. And I'd be very surprised if you came in under 6 lbs with fully loaded 30 round mag and optic.

This is a 5.88 lb rifle with loaded 30 rounder (M193), back up sights and micro RDS:

No mag:

I did it for just over $500, but the Trijicon MS04 was free, I made many parts from scratch with Ti and Al, it is built on a polymer lower (4 ounces), and did all the lightening work myself, including turning the $95 14.5" M4 barrel down to sub-pencil .540". Made 1.01 ounce 7075-T6 mount for the MS-04, pinned Ti muzzle brake and 7075 Aluminum receiver extension nut with no plate.

Carved up the upper and bolt carrier, shaving about 4 ounces there

Milled on the hand guard. IIRC, it came in at 8.8 ounces with barrel nut after cutting

7075-T6 selector, .2 ounces

A carbon fiber or KMR handguard and Mag Tactical upper would be slightly lighter, but at a huge cost increase. Shaved A2 grip or K-grip is a tad lighter than the Hogue, but I hate them. Polymer FCG I'm not OK with.

But to come in at 4.87 lbs unloaded without being able to do so much of my own work? That's a 4 figure proposition.

 

[adcoch1]

I built a sub 6# carbine by using a pencil profile(9/16" diameter) 16" barrel and a lightweight 12" freefloat handguard, cheepo m4 stock, no dust cover, magpul grip etc. That was with a 20rnd pmag, and it handles wonderfully. And I believe I'm still under $600 bucks. But I turned down my barrel from an M4 proflile, so it was cheap.

By the way, a fluted bull barrel is supposed to retain the rigidity of a full bull barrel, but add surface area in the flutes to shed heat faster, and by having less material, be lighter than the same diameter barrel. All true, but not enough in practical use to really show up that much. And it costs a lot, but it looks cool. In fact, looking cool is the reason a lot of people own ar15 rifles at all. Hence the proliferation of M4 cut barrels...

 

[adcoch1]

Sorry, it isn't letting me post the picture...

 

[R.W.Dale]

Everyone has the drawer of AR parts that contributes to the next build supplying the bbl nut and FCG parts for mine. Either way these small parts don't add to the cost much.

Again I'm at 5.8 lbs with an unloaded P mag but with a REAL riflescope 2-7 leupold.

I don't really subscribe to the "with a 20 RD mag loaded" as a useful metric. First off my ammunition is significantly heavier and second lightweight arms almost universally are marketed to be carried a lot and shot a little. My ideal ammo load is 5 rounds.

I'm leaving a lot of weight reduction on the table with a steel bbl nut and full delta ring for handguards and a 300bo barrel that can still lose some diameter in front of the gas block. But that's the price I pay to be as "retro" as possible

 

[MachIVshooter]

Everyone has the drawer of AR parts that contributes to the next build supplying the bbl nut and FCG parts for mine. Either way these small parts don't add to the cost much.

Again I'm at 5.8 lbs with an unloaded P mag but with a REAL riflescope 2-7 leupold.

I don't really subscribe to the "with a 20 RD mag loaded" as a useful metric. First off my ammunition is significantly heavier and second lightweight arms almost universally are marketed to be carried a lot and shot a little. My ideal ammo load is 5 rounds.

I'm leaving a lot of weight reduction on the table with a steel bbl nut and full delta ring for handguards and a 300bo barrel that can still lose some diameter in front of the gas block. But that's the price I pay to be as "retro" as possible View attachment 227029

You neglected to mention it was on a Cav arms lower. Yes, you can save a lot of weight there if you don't mind the look. Some folks like them. Personally, I wouldn't take one if it were free.

 

[R.W.Dale]

You neglected to mention it was on a Cav arms lower. Yes, you can save a lot of weight there if you don't mind the look. Some folks like them. Personally, I wouldn't take one if it were free.

I mentioned that particular lower numerous times.

NOBODY actually reads comments in full unfortunately

 

[MachIVshooter]

I mentioned that particular lower numerous times.

NOBODY actually reads comments in full unfortunately

Not when listing out parts for that build, you didn't:

Not necessarily

You just have to take the big savers. I.e. Aluminum carrier and lightweight buffer.

My build list
Ar15 build

Lower $120
Trigger pins $6
Vise blocks $15
Mystery bbl $134
Carbine handgaurds $29
Charging handle $15
LPK $35
Bolt carrier $206
Upper $45
Buffer $30
Bolt $30

ETA I missed the loaded 30 RD mag.

But honestly who builds an ultralight to burn through mags for fun.

 

[R.W.Dale]

The other two big weight savers. The Wiskey Arms Aluminum carrier and Taccom Buffer which is little more than two plastic spacers to hold the mainspring

 

[R.W.Dale]

Not when listing out parts for that build, you didn't:

So you just refused to read the couple paragraph explaining the cav15 benefits literally one post above the one you are so stringently adherent to citing? If you are going to disrespectfully quote me like I don't know what I wrote at least have the journalistic dignity to read my posts FIRST

Or the time on page one where I discussed it as well even posting a link to the same picture.

With your skills you could build an incredibly light AR if you would build one out of lightweight parts rather than just milling a bunch of holes into heavy AR parts

 

[Tirod]

I built a 6.8 and it came in at 6.5 pounds no mag or optic. There were no high dollar exotic parts.

ARP Recon profile 16" barrel.
BRT Covert flash hider
APEX 14" Gator Grip free float (very little CNC venting)
A3 LAR upper
AGP lower
Some GI LPK
PSA carbine tube and buffer
MFT Minimalist stock

The barrel profile, gas block and rear stock are the top three items to consider. Not kitting it out with redundant optics or dead weight like slings, rail covers, lights, batteries in the holders, grip accessories, a cleaning kit, etc is what keeps the weight down. The working field soldier even leaves the BUIS back in his duffel bag, every ounce of dead weight gets trimmed when you are on patrol 6-10k. Ammo and water is more important.

Light weight ARs near 6 pounds are easy to build. It's not clamping on a whole bunch of tactical goodies that is hard.

 

[Forsaken]

 

[Forsaken]

and this is very Light weight as well

 

[chicharrones]

Please tell us more details about your build.

 

[Browning]

I would vote that anything under 6 lbs is a true lightweight, that anything between 6 and 7 lbs is a middle weight, that anything between 7 and 8 is a light heavyweight and anything above 8 is starting to become a fat girl unless it's a precision build.

 

[Forsaken]

Please tell us more details about your build.

i did not build or own that myself, but i did had the chance to fire one at the range with carbon fiber like that, and it was light.

On the Other hand, i can tell you everything you want to know about this Pistol

Upper: Radical Firearms
Barrel 8.5 300 AAC
Lower: Spike's Tactical with Spike's LPK
Pistol Buffer with shockwave Brace
NStar Sight with MBUS
Weight: 4.1LB Empry

 

[Forsaken]

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

er…No
I will gladly live with a few more ounces for a critical part that will last a lifetime than a breakable part that will leave the gun useless. Beside I already have Anderson Lowers.

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

What is a fluted barrel and the differences between it and a pencil barrel?
-A: Fluted barrel are used to increase the surface area (helps with cooling) and reduce weight while keeping a Bull/Heavy Profile
-Pencil barrels are skinnier than a regular barrel to reduce weight but are not heavy/bull barrels, they are just skinny.
Fluted barrel

fluted barrel (left) pencil barrel (right)

3. The stock. Use a skeletonized stock.

Suggestions?
A: i use the old M4 style Stock, and i love it.

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

I had not thought of that. I do like the looks of the Magpul SL handguard.

5. Eliminate the dust cover over the bolt carrier.

Check. I am probably going to use Anderson slick side receiver with no forward assist, brass defector and ejection port cover.

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

Check. It is the only way I can d-i-y with a 14.5” with a permanently attached flash hider

 

[Arizona_Mike]

See my thread here with detailed parts lists, etc.: https://www.thehighroad.org/index.php?threads/finished-my-ultralight-ar-build-pics.766900/
I think Dropbox is going to end public folder support by the end of the month, and all my threads for the last several years are going to have broken picture links, so check it out ASAP.

I love mine and have carried it on many hikes and nature walks. Most of the extra weight I carry has nothing to do with my rifle I'm afraid.

Mike

PS. Taliv started a nice ultralight build about the same time I did but finished before I did. Search for his as well.