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Discussion Starter #1 (Edited)
New Project light weight 3.26 pound 6.8 SPC II

December 6, 2015 down to 3.26 pounds (without scope). No way did I ever think that was possible out of a legal 16.1 inch gun. My AR 308 with 18 inch barrel now weighs less than what I achieved in July of 2014 on the 6.8 SPC.




PSA CHF Stainless AR-15 Barrel 6.8mm Remington SPC II reprofiled to 16.1" 1 in 11" Twist Stainless Steel Gas Port Location: Mid-Length, Gas Block Seat: .750" Diameter Weight: 21.95 oz. Target crown
<o:p2A Balios Upper 6.5 oz. stripped, no FA
BAD gas block titanium 0.58 oz. (saves .85 to 2.5 oz.)
Mid length gas tube 0.75 oz
ejection cover/ pin and spring - deleted
Titanium Firing pin
Rubber City adjustable carrier key
Whiskey Arms with adjustable carrier key same weight as standard key 3.91 ounces ($200)
bolt+ firing pin+ cam pin + 2.04 ounces (BCG 5.95 oz.)

Charging handle 1.3 oz.
Cobra Tactical 9 inch Mid 2.4 ounces plus 1.15oz. DPMS bbl.nut = 3.60 oz. with 3 titanium screws
DPMS BBL nut cut @ 1.15 ounces
<o:pLower: Mag Tactical lower @ 5.845 ounces
Smoke Composites open stock buffer tube @ 3.5 ounces w castle nut
carbine buffer no weights 0.90 ounces
New Frontier Accu-group polymer trigger 0.65 ounces
MagPul K grip trimmed inside to 1.7 ounces
Titanium grip screw 5 grams
V7 ultra light mag catch/release tool steel (UL-MAG-CR)
V7 aluminum/titanium selector
2A titanium drilled through takedown pins
Action spring 1.2 oz.
titanium bolt catch plunger, titanium trigger pins, titanium buffer retaining pins (eBay)


Scope and mount
Aero Precision one inch @ 2.98 ounces
Leupold scope 4-12x40 scope @ 12.25 ounces








I can hardly believe I can build a AR15 6.8 SPC that is lighter than my Savage bolt gun that weighs 6 pounds 15 ounces with scope.

This project started in June of 2014, just hoping to get under 6 pounds. Used 4 different barrels, 3 different receivers and numerous buffer tubes and stocks.

Going with a 3.1 oz. one inch Aero Precision scope mount and my Weaver 3-10x38 scope @11 oz. total 14.2 oz.
That would put total rifle at 66.3 oz, or 4.14 pounds with scope.

Note: JP Enterprise aluminum carrier is the lightest @ weighs 3.76 ounces ($339).
Ballios Lite lower receiver weighs 6.5
Mag Tactical has the lightest upper, stripped it weighs 4.8 ounces, add the .324 ounce V7 forward assist and it would still be the lightest by 0.6 ounces
<o:pBattle Arms upper weighs 6.31 ounces, their lower weighs 6.84 ounces
2A titanium pins with hole through weighs 5.1 grams
V7 titanium pins without hole through weighs 8.9 grams
Battle Arms titanium pins 8.18 grams

ALG QMS mil-spec trigger: 2.55oz
-LMT 2-stage trigger: 2.25oz
-Geissele SSA, SD-C and SSA-E, SD-E: 2.25oz
-Geissele SD3G: 2.25oz (w/4.5# spring 2.3oz)


9 inch AP Custom tube weighs 2.55 ounces
CTS 9.5" tube weighs 2.45 ounces
eBay 10" CF @ 2.40 ounces
KMR10 handguard by Bravo Company @ 162g /5.5 oz using titanium BBL nut


Aluminum 5 round magazine 2.0 ounces 5.15 oz. with 5 Hornady 120 SST
</o</o</o
 

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Discussion Starter #2 (Edited)
Carriers w/ gas key installed, in descending order of weight.

Young heavy carrier 10.5 ounces

DPMS M16: 9.5oz / 270g

Colt M16: 9.4oz / 267g

LMT enhanced M16: 9.25oz / 262g

LMT enhanced semi: 9.15oz / 259g

LMT enhanced skeleton-ized M16: 8.2oz / 232g (attacked this with a mill in garage one day.. scalloped out rear top & bottom)

Young Super lite stripped carrier no key weight 6.35 ounces $140

Integrity Arms melonite light weight at 7.1 ounces and $76

TS Arms coated steel at 7.02 ounces $233

Rubber City LMOS weight 6.9 ounces $149

JP-Enterprise JPBC-3 stainless low-mass: 6.55oz / 186g $215

Rubber City titanium w key 5.8 ounces $259

JL Billet AR 15 titanium w key ?? ounces
<O


V7 titanium w key 5.7 ounces $326

Rubber city titanium w key weighs 5.65 ounces $320

Boomfab titanium weighs 4.40 ounces w key $479

The Whiskey aluminum weighs 3.86 ounces with key $200

The JP Enterprise aluminum weighs 3.76 ounces w key $339

Last year there was the JPE LMOS and nothing else, amazing the selection and price ranges now.

Check out a partial list at http://www.recoilweb.com/preview-gui...ups-65941.html
 

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Have you looked into a Christensen Arms AR carbon fiber barrel? That help cut down the weight a little too. Not sure if they have the 6.8 option yet though.
 

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Discussion Starter #4 (Edited)
Have you looked into a Christensen Arms AR carbon fiber barrel?
Have you looked at their prices???
I can build a couple of guns for the price of one of their barrels.

I have heard some not nice things about their accuracy. Wilson Combat has a GREAT reputation, and by the way are a BIG sponsor.
 

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Discussion Starter #5
I was hoping my PRI and the Kies adjustable gas blocks would be lighter, but no joy. The Kies weighs 1.60 ounces, the Kies mid gas tube another 0.75 ounces. My stainless PRI gas block also weighs 2.35 ounces with the mid gas tube attached..

So I had to order the V7 titanium 0.75 ID gas block. At 0.75 ounces it saves a lot ( 0.85oz.) for the money $68.

I had a brain fart, I was thinking of my ALG single chamber muzzle brake that weighs only 2.0 ounces. Beautifully made. But it is 223/556 and the smaller thread, not going to fit!!!
 

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Discussion Starter #6
One thing I have learned is you can weigh parts separate and they do NOT add up to the same when assembled.

My Ni coated 6.8 BCG weighs 11.30 oz. complete.


My New Frontier Polymer lower with FDE Magpul grip, FDE Super Stoc Spartan weighs 24.3 oz.

I ordered the V7 aluminum castle nut and end plate, they should bring the lower under 24 ounces.
 

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Discussion Starter #10 (Edited)
WhoDat and constructor are both correct. I have wanted a JP LMOS carrier for ever, at one time they made one @3.5 ounces. Then their stainless one came in at 6.6 ounces and supposedly the new ones @ 6.8 ounces. That cuts 2.5 ounces, takes all of ten seconds to change out. But over double the price of my chrome PSA and Ni carriers. Saving this one in case the rifle don't come in under 5 pounds.

Been looking at the Mag Tec upper and lower receivers. I just bought two weeks ago a Spikes upper and lower set in FDE. Trying to make weight using the spikes upper, and eventually the lower.
The Spikes upper weighs 7.2 oz. stripped (it came complete) and the lower 8.4 ounces stripped.

The Mag upper weighs 4.8 oz. stripped and the lower 5.875 oz. stripped. Together they save 4.925 ounces, but I would have to shell out another $346 before shipping.
So if someone else were to start with the Mag receivers and the LMOS have a nearly a half pound better start that mine.

Anyone know if Wilson Combat makes their own barrels? The 24.8 ounce 6.8 barrel would be nicer with a target crown and no barrel budge there the brake meets the barrel ridge. A little trimming on the profile at the front muzzle end might get the barrel below 24.0 ounces.


Found a lighter carbine buffer in one of my lowers, was @ 2.95 now 2.55 ounces so lower at 23.95 before the V7 castle nut and end plate. They would lower it to 23.55 oz. or 1.47 pounds.
 

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Discussion Starter #11
WhoDat, where is lanbo's? That price is great. Midway has a black one for $80 with out forward assist.

Was looking at what has become an accuracy thread, many brought up Aero precision as having a good to go flat surface for the barrel to tighten to the receiver. Does Aero precision make a good upper????

So I called Aero, the lady said a couple of emails asked how much the upper weighed. She ran back and measured a stripped upper with no forward assist, 0.4012 pounds. I thanks her and checked that is 6.4 ounces. That is 0.8 ounces less than my Spikes.

The Les Baer w/o FA weighs 6.9 oz. The Ranier w/o FA weighs 7.3 ounces. The Mag Tech weighs 4.8 oz. with FA, stripped
 

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Here's where I found mine...

http://lanbosarmory.com/index.php?main_page=product_info&cPath=24_53&products_id=18389

Sold out now, but they'll probably be back. When they are, I'll buy a couple more.

$54.49 aint' bad...



WhoDat, where is lanbo's? That price is great. Midway has a black one for $80 with out forward assist.

Was looking at what has become an accuracy thread, many brought up Aero precision as having a good to go flat surface for the barrel to tighten to the receiver. Does Aero precision make a good upper????

So I called Aero, the lady said a couple of emails asked how much the upper weighed. She ran back and measured a stripped upper with no forward assist, 0.4012 pounds. I thanks her and checked that is 6.4 ounces. That is 0.8 ounces less than my Spikes.

The Les Baer w/o FA weighs 6.9 oz. The Ranier w/o FA weighs 7.3 ounces. The Mag Tech weighs 4.8 oz. with FA, stripped
 

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Discussion Starter #13 (Edited)
That Mag Tech lower would be a great start on a lightweight lower.

Here is my Spikes lower with Vltor V5 carbine tube, Vltor V5 buffer and rifle spring, and Magpul FDE grip @ 32.65 ounces, over 8 more than my New Frontier lower. Geissele SSA-E trigger and extended take down pins.



Without FDE Super Stoc @ 26.95 oz.


Trying to see how light a aluminum lower could be built.
Mag Tech lower saves 2.525 oz.
Magpul FDE grip "K" (not K2) saves 0.60 oz.
V7 castle nut saves 0.25 oz.
V7 end plate saves 0.20 oz.
V7 mag catch saves 0.15 oz.
V7 takedown pins saves 0.29
V7 selector saves 0.26 oz.
V7 buffer tube saves 0.75 over my Vltor V5 tube
Carbine buffer @2.55 oz. saves 1.15 oz. over V5 Buffer @ 3.75 oz.

Total Mag Tech and V7 parts saves 5.575 ounces so 32.65 oz. minus 6.175 oz. equals 26.47 or 1.66 pounds.
That is less than 3.2 ounces more than the New Frontier polymer lower.


revised 6/11/14 checked weights on Spikes lower
revised 6/12/14 with MagPul K grip weight
 

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Discussion Starter #15 (Edited)
And a Hell of a lot nicer and tougher...
that's why I ran the numbers, I figured more people would like a pretty FDE or OD lower than the polymer.

Those 4 ounces puts the gun above 5 pounds, but it is just a number. Would be just as nice at 5 pounds 3 ounces.

And there is still the 5 ounces that could be cut from my upper numbers by using a Mag Tech upper.

Midway had the JP LMOS carrier for over $50 less that JP so I bought it as my fathers day gift.

I really love the Vltor V5 system, but the longer buffer tube and buffer and rifle spring are close to 2 ounces heavier.

So over the next couple of months I will get more of the V7 lower parts and try to get a lighter aluminum lower. Maybe the Mag Tech lower will go on sale again?
 

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Discussion Starter #16 (Edited)
Got the AP Custom 9 inch vented Carbon Fiber hand guard today.

Perfect example of the two parts, the 4.35 oz. AP Custom and the 1.7 oz. bbl. nut should have weighed 5.75 oz.

But Nooooooo, total weight of 6.05 ounces. I expect things like this.

 

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Discussion Starter #18 (Edited)
Revised - rechecked and found one barrel nut at 1.4 oz. and one at 1.7 oz. I used the 1.7 with the AP Custom

Now I don't know which barrel nut is standard and with is Core 15?

But how you place objects on the scale that weighs up to 11 pounds changes the weight.

Bottom line is I don't worry about weights adding up. Heavier items come in more exact, like scopes.

Should still come in under 5 pounds, stocked up on different 6.8 ammo so I can see what she will like best. It will be more of a hog rifle like my light weight Savage rifle in 6.8. That way grandson can shoot one and I can shoot the other.

Getting some of my V7 parts tomorrow. And barrel may get here Friday 6/13/14
 

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stroker: You wrote "Here is my Spikes lower with Vltor V7 carbine tube, Vltor V7 buffer and rifle spring, and Magpul FDE grip @ 32.65 ounces, over 8 more than my New Frontier lower. Geissele SSA-E trigger and extended take down pins."

FYI, V7 Weapons Systems makes lightweight parts for AR rifles. They are not the same as, or associated with Vltor. Vltor does makes a buffer assembly they call their V5 system, but its not especially lightweight. - CW

http://www.v7weaponsystems.com/

http://www.vltor.com/
 

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Discussion Starter #20
My bad, you are so correct. I could blame it on my old age, or the 106 degrees here in Lost Wages, but I simply transposed the numbers.

The Vltor V5 system is sweet, I really like it. Basically a AR10 carbine buffer, AR15 rifle spring and a longer carbine buffer.

I have the RE-A5 tube, weighs 4.25 ounces, my New Frontier 3.8 and the V7 3.5 ounces.

Vltor has two V5 system tubes, the 7 position RE-A5 and a 6 position. Trying to see if the 6 position is lighter.

Did I say, the Vltor V5 system is smooooth, sweet? I cut the V5 buffer from 6.83 ounces to 3.7 ounces using an adjustable gas block.

Since I will be using the JP LMOS lightweight carrier and hopefully the V5 buffer under 3 ounces (by swapping out a steel for aluminum plug) I will be cutting the action system by 4-6 ounces total weight. That will require an adjustable gas block.
 
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