308 AR10 Build Info/Picture Thread

#1,052
Everything in that photo is 17.0lbs, empty magazine. I do have a set of weights that add another 12oz, making it a lot more stable from a bag.

It shoots great, a little rough on brass but I’m only shooting hornady 1x or factory ammo out of it. Zero issues with feeding, extraction, or ejection ( +1.5 gas block at factory setting) using the TBAC Dominus.

The factory trigger was nice, but I’m a 2-stage guy, and the MBT is awesome for the price. It is “duty style”, heavy and definitive, with a tactile reset…not unlike the AI triggers I’m used to.
 
#1,053

Dang! That’s light, especially with that barrel. Not a knock, use what works for your needs, but why a red dot with a 20” barrel? Or I guess another way to put it “Why so much barrel for something with just a red dot?”

Again, if that works for you, cool. Genuinely curious.

- - -

And BTW, your gun looks like my light(ish) weight AR10 (pencil profile 16” barrel, and a lot of V7, Smoke Composites, etc.), and my uber-light no tax stamp AR15 build (also with a 16” barrel) had a baby that grew up to be bigger than dad! 😆





…sub 4# with a loaded mag and red dot:

 
#1,055
That’s pretty cool actually! I knew they made a 3x, but wasn’t tracking on the 5x sight.

I’ve actually been very impressed with the crispness of their dots, durability, and ability to hold zero with their advanced (higher end) red dots. I have them on a couple of the ranch rifles, and often recommend them to friends/family who want a red dot but don’t want to spend Eotech or Aimpoint money.

I only have one of their OG 1x micro prism sights with the ACSS “Cyclops” reticle on a PCC, and it works well for my needs. It’s used primarily as a longer-range tool that takes the same mags as the G21 I usually carry on the ranch, but don’t have enough rounds through that platform yet to say it’s a keeper.



Would love to get a report down the road on long-term reliability of yours; especially on a heavier caliber rifle.

Also @Top O' Texas what BUIS are you running? Kind of look like Bobro, but can’t quite make ‘em out in your pic.
 
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#1,058
gave a test run on my AR6.5PRC build and it went well, but could've been better. shot 2 rounds, ejected @ 1-2 oclock, shot 2 more after 5 more clicks out, shot 2 more with fully out and still ejected at the same as 1st 4. opened up the upper and checked the buffer.........i had a 9.5oz rifle buffer that caused this. i'll either install a standard weight rifle buffer and/or take another lower and use carbine between 3.5-4.5oz. brass looked good and ammo used was factory norma 143 golden target match which was great, cause the mag (larue) accepted the length @ 2.860". norma must've made them for short action lengths. no other factory 6.5PRC ammo to compare with as some could be for xm length mags?
 
#1,061
I apologize, missed the PRC part whoops.

Have you posted build specifics for this in another thread?

What I said is generally correct, but 6.5 PRC is a bigger case. Tuning per ejection pattern with the PRC could be misleading.

The only scenarios I’ve seen that fit your description:
1. Gas port on the small side = unresponsive gas adjustment.
2. Gas tube short not enough engagement in gas key.
3. Short dwell timing i.e. long gas system combined with shortish barrel. For #3 I’d agree, reducing buffer/carrier mass is what I would try.
 
#1,062
Build specs

McGowen 8t 22" hbar +2 gas (gas port appx .100"
KAK magnum upper
Aero lower
KAK magnum bcg
Odin adjustable block
Rifle length buffer/tune w/KAK 9.5oz rifle buffer
Mil-spec buffer spring
Timney 3# trigger
Ultradyne brake
Diamondhead handguard
Athlon 1-10x28 Helos BTR Gen2
Burris QD optic mount
L) 7/08rem
R) 6.5PRC
 
#1,063
I would check gas tube engagement for sure. Should land about middle of the cam pin cut out in upper.

Not all +2" gas tubes are the same.

Both barrels below are RL + 2" & yet tubes are not the same.

 
#1,064
straightjacket and rainier........WOW

i knew armalite and wilson had their own interpretation of rifle length, but never experience that issue with the barrel i've bought. everything lines-up (gas port to gas block, gas tube to gas key) and headspace checks out as i have go, no-go for every cartridge i shoot (takes that issue out of the equation). i've built a fair share of ar's (50+), so not new to them and stick with brands i trust and never let me down. many things are checked before assembly.
 
#1,065
also i had the 9.5oz buffer in case of over pressuring being a magnum cartridge and 1st experience with a short mag in the ar platform. i had some in .473" rim that ruined the firing pin due to op'ing (243win), so didn't want that mistake again. i have a 7saum with same gas port size and gas length (different brands of barrels), so this is a learning curve with short mag ar's.
 
#1,066
I can go be poor elsewhere, but I had to give this thing a try. It’s the PSA Sabre 10. I added the PRI Gasbuster CH, Harris bipod with QD mount, which is Lowlight’s all time favorite, a PA ACSS DMR scope, and the Surefire can. Only 40 rounds of M80 ball through it so far but not one failure and ejected at exactly 3 o’clock into a nice, neat little pile. I was able to keep it right at about 2 MOA at 100yds which is good for me because I’m not that good of a shot.











 
#1,067
Seekins SPX Builder's Kit; custom Cerakote color Accuracy International Dark Earth; 22" Rock Creek SS 5R cut rifle barrel by Craddock Precision; SLR SL8 0.875" adjustable gas block; OSS/HUXWRX 7.62 muzzle brake, an amazingly effective yet not obnoxious muzzle device; Geissele 7.62 Super Charging Handle (SCH); JP Full Mass Operationg System (FMOS) bolt carrier group with High Pressure Bolt (a must with the 6.5 CM); TriggerTech Diamond trigger, set to 2 LB, riding on V7 titanium fire control pins; Seekins ambi safety; BCM MK 2 lower receiver extension with H3 buffer and JP polished recoil spring; Hogue oversize pistol grip; BCM SOPMOD buttstock; Magpul 20-RD magazine.


 
#1,069
This is becoming a favorite of mine for all around use and still holding good precision. Started as a lighter weight hunting build with a Proof CF 16” barrel that was a hammer, but that barrel hated a suppressor. So I fell back on a RA Ultramatch for the heavy flutes to help with weight that’s becoming my go to rifle now.

  • Holosun 509t green mrds
  • A10 suppressor
  • Adm delta 20 moa mount
  • 16” Ultramatch
  • Superlative gas block .750
  • Geissele SD-E trigger
  • B5 Precision-
  • Fab defense FDE bi pod
  • Cmmg zeroed mk3 lpk
  • Lmt mws buffer system
  • Warhammer FDE charging handle
  • BCM qd sling mount
  • GroveTec Sling
  • Magpul K2+ FDE grip
  • FDE dust cover
  • Ggp AR10 builder kit OD green
  • RCA bcg
  • Trijicon 3-18 Tenmile
  • Ariska offset and plate


 
#1,071
when shooting i used factory hornady 123sst and amax ammo. shot once then shot a second time, thought i missed so went and checked and found that the 2nd shot was almost exactly in the 1st (just slightly oval). that cbi barrel is a keeper for sure!
 
#1,072
I am using a KAK Industry BCG and the standard PSA buffer but I have an adjustable gas block up front that I tuned to give just enough gas to hold open on an empty mag. Muzzle Brake is an AR-Stoner. I was using Hornady 130gr ELD Match the picture is with RL15 and I have a batch with Varget I need to test as well.
 
#1,073
Also, one thing I wound up doing was putting some shims between the barrel and the upper receiver to get the feed ramps a little closer. Used an Aero Precision Barrel Shim Kit LR-308; they managed to go behind the index pin without me having to cut them like I have seen in some videos.
 
#1,075
Gotta fresh one here.....

18" barrel from Craddock Precision in 6.5 CM (Criterion blank, rifle +1)
SMF Tactical TAC-10 upper
KAC URX4 15" handguard (paint to install, lol)
Superlativer Arms AGB
JP LMOS full BCG

Lower is a Larue complete (other than the ambi end plate and a silent capture spring).

Weighs 8 lbs 14 oz stripped. Look forward to running this suppressed in next few days.

 
#1,077
-M5 registered SBR receivers, trued, shimmed, glued
-Rainier Arms Ultra Match 308 Win MLGS barrel 16" cut down to 12.5". .0715" gas port
-Low Mass carrier, 2.2oz buffer, red Sprinco Spring.
-Aero AGB
-Whatever the cheapest Geissele trigger is. It's mediocre.
-7.3lb base weight. Kinda porky.

This started life as a barrel I took out of another gun due to dwell problems with the MLGS. Cutting off 3.5" of barrel completely resolved the early unlocking. The gun runs with full mass and low mass BCGs. It has enough gas for -20f weather, with and without the silencer, FMOS and LMOS. The scope is a cheap placeholder until I decide what to do with the gun


 
#1,081



Noveske N6 Recon
Proof Carbon 22” 6.5cm
Superlative Adjustable Gas Block
Magpul Gen 3 PRS Stock
Area419 Arca Rail
Geissele Trigger of some sort (will be swapping to a TriggerTech)
JP VMOS BCG w/ HP bolt
JP SCS
TBAC Magnus SR
TBAC Bipod
NF ATACR 4-20

16.8lbs as pictured
 
#1,083
Barrel extension outside diameter is the other potential variable in the upper-to-barrel fit equation.

I only build SP10's with Craddock or Proof barrels. Both are a snug fit in the Seekins upper, and thermal fitting is usually required.

I have a good deal of exposure to the 22" SS barrel with suppressor in the Seekins SP10 kit. One of my top shooting buddies had me build one just like this for him. He's using a HUXWRX Flow 762 Ti. He gets sub-MOA 10-shot groups with Federal GMM and their 140 Match Kings.

He's got about 300 rounds through it and has never cleaned it. No telling how well it might shoot if he bothered to punch it out.
 
#1,086
While some may decry PSA, their large frame receivers are very serviceable as long as you keep an extra bolt catch or two on hand. This is coming from a guy who has used a bunch of receiver sets from old school DPMS to LMT to SR-25. Very functional basic build.
 
#1,087
It’s a long story, but I ended up with 2 bolts for my Ar-10: the nice, smooth nitride one from my RCA BCG, and a phosphate Fulton Armory one that got sent free with my barrel. The Fulton Armory bolt is headspaced for the barrel; the RCA is not, but the bolt closes over a round and there are no problem signs on fired cases (to my very limited knowledge). Could I expect better accuracy from the headspaced bolt? Is it worth switching out and shooting a ton of groups to see?
 
#1,088
No. Have you measured case shoulder growth on fired brass from both bolts to compare? What kind of ammo are you shooting? Factory or reloads? Do you have a headspace comparator?

People get too wrapped up around headspace imo. It's important, sure, but not as important as some people make it out to be. A lot of people believe your gun will blow up if your headspace is a couple thou long. Not the case. Where you get explosions are from unsupported case webs which comes from improperly chambered barrels. This will have a component of headspace involved if this happens but the explosion comes from too much clearance between the bolt and the back of the breachface which leaves case walls unsupported by the chamber. So the case is unable to contain the explosion on its own and blows out the wall of the case, often separating the case head. Standard casehead separations when the case is supported by the chamber are relatively non-events. May stop your shooting for the day and cause you to try to figure out how to remove the body from the chamber, but they aren't going to blow your gun up. If you're headspace is too long(or you keep sizing brass too short, under headspace) you will eventually get excessive case stretch and separate a case head. So people extrapolate case head separations from over stretching brass to case head separations in unsupported chambers and say that too much headspace will blow up a gun. As far as too short a headspace, it's self correcting. You simply wouldn't be able to chamber a round.

As far as accuracy, people fireform BR brass into Dasher brass all the time which is basically just stretching an under headspaced cartridge to a chamber headspace. And most people's fireform loads shoot extremely well.

Before I would worry about anything with those two bolts, I would measure your loaded ammo from base to shoulder using a headspace comparator and the measure the fired brass the same way. For each bolt. That will tell you the difference in headspace between the two. There is some variation in that because you won't always get full case growth in one firing but that's also kind of the point. Even with a properly headspaced bolt/ chamber, factory ammo has to come in under the headspace length to ensure it chambers in a variety of guns. I've seen factory ammo and virgin brass measure as much as 9 thou shorter than reamer prints. And then when fired once may still be shorter. Could take up to three firings. So, by nature you're almost always going to have a little extra room in the chamber, and frankly you want it that way. SAAMI headspace specifications are like load ratings on tires. You should try to adhere to them. But if exceeded a little bit every once in a while you're not going to end up, upside down and on fire.
 
#1,089
I just got a Seekins builders kit and slipped a Proof barrel into it. It was not snug. I'm rebarrelling to a custom chambered Mullerworks and using an Etune 6.5 extension so it doesn't really matter but guess I got an upper built on a Friday afternoon. I'm interested to see if the Etune extension is snug. If it's not, my Smith is just going to loctite it.
 
#1,096

For shooting off a tripod, I dont stand fully upright behind my rifle.
I dont think anyone does much?

There is a really great tutorial on tripod shooting somewhere here on the Hide, stickied. See link below.

10” shorter than your height should be plenty easy to plant behind and lean into a bit.

 
#1,097
As Powdahound said above, you won’t be standing completely upright.
Even at 6’10” I’d suspect the 71.1.” plus rifle/scope on top will be satisfactory. I’ve been seeing a few of these RRS tripods pop up used lately.
 
#1,099
I am 6' 4" and a TVC-34L is high enough for me, plus about an extra 1.5". Fully extended the top of the ring(not counting the leveling base) is 68" on mine. I'm using one of the old leveling bases. The top of the base is 69.5" and once I mount my Binos, the center of my Binos eyepiece is 71.5". I have to take about two inches out of the legs to put the Binos at eye level in a fully erect stance.

If you're shooting off the tripod, you will have to take much more out of the legs, whether you are bending at the waist or standing fully erect.
 
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