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Discussion Starter #1 (Edited)
GOAL MET 9/30/2015 @ 82.30 ounces or 5.15 pounds
October 30th at 80.05 ounces or 5.003 pounds.
October 31st at 79.85 ounces or 4.99 pounds.
January 5, 2016 at 77.45 or 4.85 pounds


I really liked my last build with my old DPMS lower and a SAA upper that I hated. Loved the Faxon barrel with light weight and great accuracy.

But I wanted to explore the limits of an AR 308 Generation 1 build. So all new stuff.

Weight of rifle without scope is 87 ounces or 5.44 pounds.


Weight with previous Vortex scope and Aero Precision mount is 6.997 pounds. This is lighter than most AR15's with no sights!


The big changes are the Juggernaut Tactical 18 inch fluted barrel at 33.8 ounces. A big plus for me is the 5R rifling. Used in Marine sniper rifles and in my Savage 10TR that shot 3 bullets in one hole!
Price is very good, shipping was quick and so far my last three shots (out of 23) were MOA. One big thing is how fast the fluted barrel cools down, the Faxon barrel heats up fast and stays hot for a while. The JT heats up slower and cools down much faster. Now if you are hunting it wouldn't matter al all, one shot one kill. But maybe hogs if you get extra shots it will stay better. Only time will tell as I am not going to over heat this barrel just to prove anything.



 

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Discussion Starter #2 (Edited)
Starting break in using Norma 150 grain, lowest amount of burned powder of any brand. Shot one box and then switched to 3 rounds of Federal Gold 175 SMK's. Held over the bulls-eye and then kept next two shots aimed at the same point. Just a tease on how it will shoot. 100 degrees and wind less than 5 MPH. I was over gassed and adjusting the adjustable carrier key but still ejecting at 1:30. Next trip more adjustment.


Lightest AR 308 Generation 1
Just getting started on another new AR 308 build. My previous build I got the 7.7 pound AR308 down to 5.735 pounds without scope, 2015 we are just starting to get better choices in parts.

The goal is under 5.3 pounds using DPMS Gen 1 pattern parts.

Upper Parts: Total 61.22 ounces or 3.82 pounds

Juggernaut Tactical Arms 18 inch fluted barrel @ 33.8 ounces
2A titanium gas block @ 0.6 ounces
Gas tube mid length @ 0.70 ounces
titanium muzzle brake @ 0.67 ounces
DPMS Aluminum barrel nut @ 1.20 ounces
AR308 carbon fiber hand guard 1.6 ounces in mid length
Titanium 308 BCG @ 11.80 ounces
Charging handle @ 1.15 ounces
Tactical Machining Upper receiver 7075 T6 @ 9.70 ounces



Lower Parts: Total weight 21.25 ounces

Tactical Machining lower 11.20 ounces
Mag Pul K grip .
V7 aluminum grip screw
V7 Mag catch aluminum
V7 Aluminum selector 90 degree
2A aluminum AR308 takedown pins .
V7 lite tool stel bolt catch .
Smoke Composite stock 3.5 oz.
AR308 carbine buffer (no weights) 0.85 oz.
NF polymer trigger group 0.65 oz with titanium trigger pins

DPMS carbine buffer spring
Titanium buffer retainer, mag catch plunger
Carbon fiber pistol grip cuts 0.2 to 0.5 ounces over trimmed MagPul K grip


Smoke Composites super lite 3.5 ounce "open" stock



Tactical Machining receiver set upper at 11.7 ounces and lower at 11.20 ounces
 

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Thanks Breaststroker, another interesting thread on a topic that has been elusive. I have always been interested in a 308, but just too massive.
 

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Very nice indeed!!! I like the JT fluted barrel a lot. The 180 Barnes TTSX that I plan on using wants a 1/11 twist, the only reason I might opt for the 18" BHW 1/11 poly barrel. Really like the JT fluted though.
 

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Discussion Starter #5 (Edited)
The 1 in 10 JT shoots 175 grain nice, pretty sure another 5 grains won't change accuracy. Not only light weight and purty, but available without a wait. At $299 it is a steal, fluting like that usually adds $100-150. For $30 more they will black cerakote it. Usually the 5R polygonal grooving both increases velocity and accuracy.

Actually 99% of 308 ammo is made for bolt guns. Zeidecker speaks to this problem with his articles about AR 308s and M14's.

I have one bolt and 3 AR308 uppers, every gun seems to prefer heavier ammo with Federal Premium Gold 175 Sierra Match Kings shooting the best in the AR308's.

If I lived in Florida or other states without huge mountains, I would go with my DPMS SASS heavy (58 ounces) barreled upper. At 7.6 pounds without scope, it is lite enough to carry easily and NOTHING is more accurate from cold bore.


Juggernaut Tactical Arms
• Barrel Length: 18"
• Gas Block Seat: .750
• Rifling: Polygonal 5 Groove
• Weight: 32.0 oz actually 33.8
• Stainless Steel: 416R
• Feed Ramps: M4
• Gas System: Midlength
• Chamber: .308
• Finish: Matte Stainless
• Twist: 1X10
• Thread Pitch: 5/8X24
• Testing: MPI tested
• Made in the USA!

 

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Discussion Starter #6 (Edited)
I have to revise this post as I will soon be @ 5.1 pounds.

I was actually hoping to get down to 5.2 pounds, but with existing hardware that is impossible. I am at 87 ounces right now. I will probably be able to cut another ounce or two soon.

Supposedly H made a very lite 308 barrel, must have been less than 30 ounces.

Faxon Arms is working on a lite weight barrel, again hopefully under 30 ounces with 28 ideal. This would cut 5.8 ounces and 8 full ounces over their mid weight barrel.

Battle Arms is working on 308 receivers and perhaps 2A will produce a receiver set under 20 ounces. The Tactical Machining set weighed in at 22.9 ounces. This would cut 3 ounces

And at least one company I know of is working on a titanium carrier. This would cut 3 ounces over the JP LMOS

All of the above will be here by early next year. Actually some one could build a 4.9 pound AR 308 right now by cutting the JT 18 inch barrel one inch. That would cut 1.5 ounces of barrel weight and 1.45 ounces of titanium brake weight.

So THIS year it should be possible to build an ultra-lite weight AR 308 under 5 pounds. What it really means is you can add your favorite handguard, grip or butt stock and still be way under 6 pounds.
These would be more hunting MSR's, suitable for large elk and moose.
 

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Discussion Starter #7
I was posting on the accuracy thread about barrel nut shims and how they can greatly help in a build. Since I am going to put a different barrel nut and handguard on this build, I started searching for 308 barrel nut shims. Took over an hour, started thinking they didn't exist.

But Bison Armory has them!!!! Under accessories only $5 for three. Shims take a while longer to time, but all my 6.8 and 556 rifles use shims and they are all sub MOA, just saying.

New to shims, read this: http://www.ar15barrels.com/data/barrel-nut-index.pdf Randal has a lot of great info on his site.
 

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Good info; I lapped my 308 upper to get it timed right, wish I'd known the shims were available. (I think lapping is good, I just could have done a lot less.)
 

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Discussion Starter #9
Also have searched for 308 receiver lapping tools, can't find any yet at Wheeler, the maker of the AR15 lapping tool. Searched the internet. Some home garage lathe person could make an AR308 version and they would sell great.

There are now over 23 companies making receivers for AR 308's. Any many more making 80% lowers.

Finally got the Tactical Machining bolt catch rod. Much different that the DPMS which was a rod with a threaded section, probably 6/32 thread.

But Tactical Machining uses a straight rod and a smaller allen 4/40 to hold the rod in place.

They also included another 4/40 allen to hold the rear takedown pin spring in place. Since I have about 80 4/40 allen screws left I used one of mine last week to put the lower together.
This is different again from the DPMS lower that inserts the rear takedown detent and spring from the bottom of the receiver next to the selector spring.

Now I am waiting for the V seven tool steel bolt catch, ordered one for my 3.5 pound 6.8 and one for this 308 build.

Talked a while to the V7 people, I thought I knew why they didn't make a titanium bolt catch, and just as I suspected titanium can't take the hammering like tool steel can. Also no selector detent in titanium. They won't be doing any 308 receivers for a while, swamped with orders.
 

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Discussion Starter #10
One of the great shooters is David Tubbs, he has loaded 308 ammunition that has special bullets with grit built in that when used properly will decrease group size up to half.

My DPMS SASS had a Teflon coating and the Faxon Arms was melonite coated.

But the new Juggernaut stainless barrel is a great candidate for the 308 FinalFinish + TMS Loaded Ammo Complete Care ProPack. Expensive at $82 but gives me something to try to increase accuracy.
 

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QUOTE=breastroker;671488]One of the great shooters is David Tubbs, he has loaded 308 ammunition that has special bullets with grit built in that when used properly will decrease group size up to half.

My DPMS SASS had a Teflon coating and the Faxon Arms was melonite coated.

But the new Juggernaut stainless barrel is a great candidate for the 308 FinalFinish + TMS Loaded Ammo Complete Care ProPack. Expensive at $82 but gives me something to try to increase accuracy.[/QUOTE]

let us know how that "tubb's fire lapping" goes....I have heard both positive and negative things on it but never known anyone who has actually used it....I heard they are good for revolvers too, but again never known anyone who has tried ....some other "great shooters" and match barrel makers say to never use any type of grit in a barrel, it just shortens the life of the barrel..not sure who to believe
 

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Tim_W has an excellent thread (STICKY) at http://68forums.com/forums/showthread.php?10884-Tubbs-Final-Finish-Load-Data

I am going to follow his advice as it seems on point.
I saw that thread a while back, I also noticed elkbow's post on the last page.....I've also seen world class rifle shooters/barrel makers that say NEVER use bore paste or ANY abrasive inside your barrel, some don't even recommend any brushes. that's why I'd like to see more before/after info of people that have actually used the system .....so make sure you post up your before/after results for others to see.
 

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let us know how that "tubb's fire lapping" goes....I have heard both positive and negative things on it but never known anyone who has actually used it....I heard they are good for revolvers too, but again never known anyone who has tried ....some other "great shooters" and match barrel makers say to never use any type of grit in a barrel, it just shortens the life of the barrel..not sure who to believe
I've used it on a number of rifles. I like it, but call b.s. on the claim that it cuts group sizes in half. Maybe that's because my rifles already shot well though. It definitely makes the bore easier to clean, and practically eliminated copper fouling in my rifles. You may find an improvement in accuracy (I've never seen it get worse in my guns), but probably not as much as the advertising claims.
 

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Discussion Starter #15 (Edited)
Shot a box of 168 grain SMKs, about 1 to 1.2 inch groups. One dump of ten rounds with decent group.

Then shifted to Gold 175 SMKs and groups started getting better, under one inch.

Then cleaned the snot out of BCG and barrel, told the RSO that stainless barrels usually start getting better after 60 to 80 rounds.

So here was shot 61, wind less than 5 MPH, 80 degrees:


About 15 seconds later shot #62 different target:


Another 15 seconds and shot at a target with about 20 rounds of 168 in it, but another bulls-eye a quarter inch to the left of dead center zero.

The 168 was ejecting at 2 PM after 4 adjustments, when I switched to the 175 PERFECT 3 PM ejection. Federal Premium Gold medal 175 grain Sierra match Kings always brings a smile to my face, sweet!!!!

Can't wait to get this out to 200 yards.
 

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Discussion Starter #16
THM
I've also seen world class rifle shooters/barrel makers that say NEVER use bore paste or ANY abrasive inside your barrel, some don't even recommend any brushes
Those shooters are using true match barrels in the $800 to $2000 price range. The whole Tubbs system would not be needed.

But for those mortals than can only afford a $300 barrel, the Tubbs system MAY help. Most CNC produced barrels have potential for great accuracy, the Tubbs system just knocks off the burrs and polishes the rifling.
 

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Discussion Starter #17 (Edited)
@ 5.30 pounds now

Thanks to Joe I now have the lightest AR 308 Hand guard anywhere! With three titanium holding screws total weight was 2.97 ounces. Previous hand guard was 4.75 ounces so able to cut 1.78 ounces off the upper. I also like the looks slightly better
@2.95 ounces with out screws:


Longer than last hand guard at 10.5 inches:


Upper assembled with three titanium M4 screws.


Would have cut another .11 ounces if the company I ordered a titanium firing pin from sent the wrong thing TWICE. Titanium won't be picked up with a magnet!

I should be at 84.9 ounces, will weigh tomorrow as I had the scope off for upper work. That's 5.30 pounds.

I just might make my goal of 5.20 pounds this year, fingers crossed.
 

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Certainly appears to have the accuracy, but that's just too light. Recoil with that skeleton metal butt stock has got to be brutal. 8.5 lbs would be a lot easier on the shoulder.
 

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Discussion Starter #19 (Edited)
I have a very bad shoulder. To sleep at night I put a Salon-Pas on the shoulder and take 2 Naprosyn. There are days it hurts so bad I have trouble lifting the arm to shoulder level. That is the reason I got into 6.8 SPC II shooting.

So every time I shoot this new AR 308 I smile because the recoil is so much less than a standard AR 308. The combinations of a good two chamber muzzle brake, an adjustable gas system and a huge weight reduction in the action weight makes the recoil just a little bit more than a 6.8 SPC.

I am amazed when I start adjusting the gas system, with no adjustment recoil is pretty bad (for me). But by the final adjustment recoil is about 50% less. And that is with 175 grain pills. I have some 125 grain recoil reduction ammo, don't need them. Saving for the grandson.

Now since I usually shoot in 110 degrees and usually wear light short sleeve shirts, I use a shooting vest (with PAST Pad) when I shoot the AR 308s. I finally have two lowers to go with three uppers.

Don't use a shooting vest for most of my 6.8's, except for the 3.5 pound, with no muzzle break that little puppy actually has a kick.

The stock is carbon fiber, smooth and very comfortable. The open version actually has a small amount of give, maybe an eighth.
 

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Discussion Starter #20 (Edited)
Pretty close 84.85 ounces or 5.30 pounds:


Scope and mount 24.5 ounces:


Goal of 5.20 pounds or 83.2 ounces are closer than ever. Either a titanium carrier or that polymer lower at 5.85 ounces would get me to the goal. The polymer lower would cut 5.35 ounces so weight would be 79.5 ounces or 4.9 pounds. That is lighter than my 6.8 last June when I started it on it's journey to 3.5 pounds.

Just noticed Tennessee Arms has revised their lower weight
Estimated Weight is sub 6.5 ounces
 
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