AR10/.308 AR Build knowledge thread.

[TacticalMark]

Just posted some updated/additional info.
Fair to say the Genie is out of the Bottle - building AR308's is here to stay and getting more mainstream - almost logical considering the saturation point we've reached with AR15/M4.
Therefore like to see if those of us having built their own AR308/AR10 can weigh in with their experiences and share some of the specific issues they dealt with and solutions, things for manufacturers to consider.
If we take charge of the narrative we get the products we want/need.
Thanks.

What length spring did you use with your Vltor AE-10 and H3 (AR-15 length buffer)?

[brasse]

my first light weight AR 308 weighed 7.7 pounds using a Faxon 18 inch 36.1 ounce barrel. My last used the Juggernaut 18 inch fluted 5R barrel @ 33.8 ounces. And for all you that say what about the recoil, I already have it shooting soft and accurate.

I should get my 2A Xanthos receiver set late next week, have all the other build parts ready to go. Will reuse the Juggernaut 18 inch until my 16 inch X-Caliber fluted 308 barrel is finished, hoping for less than 31.8 ounces. Every part has been tested and works. The barrel is giving sub half inch groups with both Mk319 130 SOST and with FGM 175 SMKs.

The goal is under 4.5 pounds using DPMS Gen 1 AR 308 pattern parts.

My last AR308 got down to 4.99 pounds by 1/5/2016 using the 23 ounce receiver set from Tactical Machining.
The Xanthos receiver set weighs 16.3 ounces so an immediate 6.4 ounces cut.
Also latest CF hand guard is 0.2 ounces less and hoping the next pistol grip will cut between 0.5 to 0.7 ounces.

Upper Parts:
2A Armament Xanthos Upper receiver 7075 T6 9.00 ounces
Juggernaut Tactical Arms 18 inch fluted barrel @ 33.8 ounces
2A titanium gas block @ 0.60 ounces
Gas tube mid length @ 0.80 ounces
titanium muzzle brake @ 0.67 ounces
Clark Custom Aluminum barrel nut @ 1.18 ounces
AR 308 carbon fiber hand guard 1.60 ounces in mid length 10.5 inches
Toolcraft Titanium 308 BCG @ 11.80 ounces with ti firing pin
Charging handle @ 1.15 ounces



Lower Parts: Total weight ~ 18 ounces

2A Armament Xanthos lower @ 7.30 ounces
Mag Pul K grip @ 1.7 ounces
V7 titanium grip screw 0.113 ounces
V7 Mag catch aluminum 0.173 ounces
V7 Aluminum/titanium selector 90 degree 0.293 ounces
V7 aluminum AR 308 takedown pins 0.26 ounces
V7 tool steel bolt catch 0.31 ounces
Smoke Composite stock 3.3 oz.
AR308 carbine buffer (no weights) 0.85 oz.
NF polymer trigger group 0.65 oz with titanium trigger pins
DPMS carbine buffer spring @ 1.5 ounces
Titanium buffer retainer, mag catch plunger

[daddyusmaximus]

Ounces aside, what's a good quality upper to put on a CMMG lower. I need to get back to work on my .308 build...

[brasse]

Can't go wrong with Aero Precision or Tactical Machining

[the1nonly]

I have read through the posts on this and didn't see an answer to my question, which is, if I build a SR-25 20" barrel, rifle length gas, can I put an adjustable stock on? If yes what buffer, spring and tube would be best to reduce felt recoil? Should I add an adjustable gas block? Thanks in advance.

[polydeuces]

Pretty much very sure sure it's addressed somewhere but to answer your question you can go with a rifle RE and UBR (type) stock, or any AR15 type RE/Stock.
Or the VLTOR RE10 (which is the A5 for AR308), yes - with an adjustable gas block - will really help dialing it in.
Hope this helps.

[polydeuces]

What length spring did you use with your Vltor AE-10 and H3 (AR-15 length buffer)?

sorry just now caught this.
Sprinco AR308 spring.
Totally awesome.

[rpoL98]

for my AR-308 build, i used Slash's HeavyBuffer 308 carbine buffer spring, and either the HeavyBuffer 5.5oz CAR-10 carbine buffer or the KAK industries 5.5oz LR-308 carbine heavy buffer, both of these are 2.5" OAL, with the standard AR-15 M4 milspec buffer tube (7" internal depth). and then you can use any AR collapsible buttstock you want that fits on the milspec carbine buffer tube.

[the1nonly]

Thanks poly and rpol, I forgot to check here after I posted so I reposted question on main page.

[daddyusmaximus]

Is there anyone running the A5 system on a .308 AR? I'm building one on a CMMG lower (DPMS pattern) with an Aero Precision upper. I found out that they make .308 A5 buffer tubes, but no internal parts, and no complete kits.

Tube: https://www.vltor.com/shop/a5-system...ver-extension/

It says the following:

"If you are using this for a DPMS rifle, you will need to call DPMS for the correct parts needed. Attempting to use this tube with parts other than these, will result in damage to your rifle."

So I get on the DPMS site, and they don't list any parts for a fixed stock .308. It was my understanding that the A5 system uses a rifle length spring and special buffer. Now what?

This is for a SBR that will use a 12.5" Rainier Arms UltraMatch .308 Barrel. https://www.rainierarms.com/rainier-...-armalite-dpms