New lightweight AR-15 project

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NikatKimber

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As promised, individual parts weights:

Total Calculated...........80.13


Part ..........................Weight
...................................oz
Lower Half .................26.05


Lower .........................8.60
Trigger ........................1.30
Hammer .....................1.24
Pistol Grip ...................2.40
Mag Catch ..................0.40
Bolt Catch ...................0.46
Bolt Retainer ...............0.09
Safety/Selector ...........0.63
Pivot Pin ......................0.31
Takedown Pin ..............0.23
Buffer Tube .................3.40
Buffer .........................1.58
Buffer Spring ...............2.20
A2 Spacer ...................0.81
A2 Screw ....................0.22
Buttplate .....................1.76
Trigger Guard ..............0.18
Grip Screw ..................0.24




Part ..........................Weight
....................................oz
Upper Half ..................54.08


Upper ..........................5.96
Gas Block ....................1.48
Gas Tube .....................0.80
Barrel ........................24.80
Charging Handle ...........1.04
BCG ..........................11.60
Handguard ...................6.30
Muzzle Device ..............2.10

As you can see, the total is pretty close to the actual weighed part. 80.13oz separately, 80.5oz when weighed assembled. It could be rounding errors, or I forgot a part.

Next will be a list of parts used and prices.
 

NikatKimber

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$451.55 -- Total

$89.99 --- Spike's Spartan Stripped Lower Reciever
$59.99 --- Palmetto State Armory MOE QMS LPK - 28767
$15.00 --- A2 Buffer & Buffer Spring Kit
$1.99 ---- A2 Stock Spacer
$2.00 ---- A2 Buttstock Screw
$15.00 --- A2 Buffer Tube
$8.00 ---- A2 1/2x28 Flash Hider w/ 1/2" Crush Washer Kit
$6.99 ---- DPMS Buttplate AR-15 A2 Polymer Black
$39.59 --- Radical Firearms LoPro Adj Gas Block - .750"
$4.09 ---- DPMS Pistol Grip AR-15, LR-308 A2 Synthetic Black
-$20.00 -- Sell MOE+ Grip & MOE TG
$10.00 --- AR-15 MilSpec CH - On Sale
$39.99 --- PSA Slick Side Upper - On Sale
$59.99 --- Bear Creek Arsenal AR-15 Barrel, 16" LW 1:8 Twist, .223 Wylde, Mid-Gas Parkerized - On Sale
$59.99 --- Bear Creek Arsenal Bolt Carrier Group .223/5.56 - On Sale
$8.99 ---- Radical Firearms Stainless Steel Gas Tube - Mid Length - On Sale
$59.99 --- Carbon Fiber Mid Length 12" Free Float Quad Rail Handguard, End Cap with Nut


If you were buying everything up front, you could save some weight and start with the MagTactical or a Poly lower if wanted. Also, you could buy an A1 screw and skip the A2 stock spacer - I only used the A2 stuff because I had it in my parts bin. I am going to order the A1 screw.

One thing to note: if you are using a lightened action system (buffer, carrier) you MUST use an adjustable gas system. That's why I didn't use a pencil barrel with a .625 seat, since .625 adj gas blocks are uncommon, and expensive.

Additional note: some of the parts listed above are current best prices, as they were parts I had on hand and don't have record of prices, or they were take-off parts. Some of them are sale prices and I tried to note that.
 

LinearZero

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I would have to suggest anyone looking at this type of build to take a look at GWACS armory in Tulsa. I have one of their FDE lowers, which includes the lower,stock and grip molded into one piece. Coupled with a govt. profile barrel, makes a very lightweight build. I have a light on mine, but I have had several Army vets exclaim how light it was even compared to custom setups they ran. The only thing I don't like about it is the LOP/grip angle, which forces my wrist to cant forward significantly. If the LOP was longer, it would be a bit more comfortable.
 

NikatKimber

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@LinearZero
I just added the weights up, and completed, the GWACS would weigh 28.34oz, or just 2.3oz more than what I set up. If one was looking for a lightweight but robust rifle/carbine, that would be a great option.

Considering I was aiming for "as light as possible on a budget", for my application - where I valued lighter weight over durability; my setup was superior.
 

LinearZero

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@LinearZero
I just added the weights up, and completed, the GWACS would weigh 28.34oz, or just 2.3oz more than what I set up. If one was looking for a lightweight but robust rifle/carbine, that would be a great option.

Considering I was aiming for "as light as possible on a budget", for my application - where I valued lighter weight over durability; my setup was superior.
That's cool it ended up that light, I never did the math myself but thought it would be worth a gander.
 

NikatKimber

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Got the cheap brake in (compromise for now as light effective brakes are $$$), and the A1 stock screw so I could ditch the A2 spacer.

Also ordered an Aluminum 10rd mag as they are the lightest I could find.

Now I need to get it out and shoot it, and tune the GB for this setup since it has a LW operating system.

Here it is as it currently is configured. 5lbs 3.4oz with the empty mag. The brake is heavy! 3.9oz!

LW-AR-Complete.JPG
 

NikatKimber

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Alright, now that I've gotten all the factory parts and it's built, I will start on modifications to reduce weight.

Unfortunately, due to some medical issues my wife is dealing with right now, I won't be able to travel up to my friend's place in KS who has the mill I was going to use for the bolt carrier cutting. I was also going to mill on the upper receiver while there.

So far, I've played with cutting down an A2 grip. The grip I cut down went from 2.8oz to 2.4oz (66g). I have not installed it because the grip I practiced on was heavier to begin with. Another spare A2 grip I had weighed exactly the same (66g) before cutting. I will cut that one next and weigh it afterwards again prior to installing it.

Here is the first practice run:

Shaved A2 Grip.JPG
 

NikatKimber

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Ordered an NFA poly LPK. They haven't been in stock for a while, and were only $35. The poly LPK will save just under 3oz.

Also found this Aluminum bolt carrier that would cut about 5.7oz, for $160.

https://www.rainierarms.com/shooting-innovations-ar-15-lmb-low-mass-bcg-gray/

That got me curious. So I made an Excel chart to see how light one could go using some poly parts. Sub 3.5lbs is possible. Wow!

ULW Build List.JPG
 

swampratt

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That is crazy light.. I have a hard time holding a real light gun while standing up and shooting.
Maybe it just takes more practice.
But man that is light!!!!!!

7.34 lbs is what my PSA freedom stainless 16" weighs without a magazine and with aluminum lower.
OH it also has a tasco 3-9x40 scope on it.
 

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