I want to build (or maybe buy, if I must) a precision .308 gas gun

[SolidCopper]

Gents, I have been scouring the forum for info and I'm stuck in a feedback loop in my head. I want to put together a precision gas gun in .308 (because I have access to the ammo). This would be for range use, primarily, but I like to build duty-quality/reliability rifles. I had settled on Seekins builder sets for receivers/forearm because you minimize/eliminate the pressure on the barrel nut when you run the rifle on a bipod. I've discovered that they are very hard to find and expensive as hell when you do find them. My questions are these:

If not Seekins, whose upper/forearm combo is best for elimination of the input into the barrel when using a bipod? I love the direct forearm-receiver attachment but Seekins, Mega/ZEV, etc don't seem to be obtainable any more. I wish Larue had a large-frame builders set.

Am I going to spend as much money building one of these as I am buying something outright from JP (highly recommended) or an SP10 from Seekins?

I've been following @Bigjake83's posts regarding small frame precision rifle building and have used his formula to put a dandy small frame recce rifle together. I'd like to try it with a large frame.

Any input? Am I just spinning my wheels?

Thanks for your time.

 

[Landon4]

Lmt makes a one piece monolithic upper, while not cheap they are nice. I have several small frame uppers but not a large frame upper. Their barrels are proprietary though, but d.Wilson can machine whatever barrel you want to work with the platform.

 

[diggler1833]

You're going to be out ~ $1,500 for even a okay-ish build yourself, and can get to double that in a hurry if you go with the better parts.

My last large frame build was upper-mid tier parts with a few top end pieces and still cost about $2K ...and I got everything I could at discount/on sale...would have been closer to $2,600 otherwise.

I am still somewhat wishing that I'd have just bought an SP-10 and called it good...but I really have 'no regerts', because I got everything I wanted. Which brings me to my point that if you're going to buy a rifle, just to swap out a bunch of the parts to make it fit you perfectly - that you probably should just build.

 

[brianf]

If you can swing it buy a large frame.

Small frame go together like Lego’s they always work.

Large frame are much more finicky to have them run lights out.

 

[TheNarrator]

I manufacture uppers with your choice of barrel (trued), BSF, Proof, Bartlein, FN. Depending on your BCG choice (if any) you're looking at anywhere from $550 - $1900, with forearm.

I don't generally suggest standalone uppers, rather a matched upper and lower receiver CNC'd set. For range use it will be fine.

 

[Bigjake83]

Gents, I have been scouring the forum for info and I'm stuck in a feedback loop in my head. I want to put together a precision gas gun in .308 (because I have access to the ammo). This would be for range use, primarily, but I like to build duty-quality/reliability rifles. I had settled on Seekins builder sets for receivers/forearm because you minimize/eliminate the pressure on the barrel nut when you run the rifle on a bipod. I've discovered that they are very hard to find and expensive as hell when you do find them. My questions are these:

If not Seekins, whose upper/forearm combo is best for elimination of the input into the barrel when using a bipod? I love the direct forearm-receiver attachment but Seekins, Mega/ZEV, etc don't seem to be obtainable any more. I wish Larue had a large-frame builders set.

Am I going to spend as much money building one of these as I am buying something outright from JP (highly recommended) or an SP10 from Seekins?

I've been following @Bigjake83's posts regarding small frame precision rifle building and have used his formula to put a dandy small frame recce rifle together. I'd like to try it with a large frame.

Any input? Am I just spinning my wheels?

Thanks for your time.

Honestly brother, I'd just pick up a Seekins SP10 and be done with it. They're super easy to swap barrels if you're not happy with or shoot it out.

 

[SolidCopper]

Thank you all for your thoughtful responses. I will consider them carefully.

 

[Chickentoast]

If you're fine with the weight, just get the SP10. I built a lightweight large frame in 16" 308 - it was a lot more money, and I'll probably pick up an SP10 for the range anyway - different animals.

 

[AZgeek]

My experience is limited here but i did a build with high quality components except for the barrel and I was in for just over $2200. An SP 10 is really a good value in retrospect. Finding a load combo and its harmonic interaction with the gun is IMHO just as important as the build quality.

 

[Billiam1211]

So I've been tinkering with an AR-10 build for I think 8 years on and off. I started off with Aero Precision matched receivers, Magpul PRS stock, TriggerTech 2-stage Diamond, and a JP LMOS BCG. I tried 3 or 4 Ballistic Advantage barrels, a Wilson Combat Super Sniper, and a few others. Eventually last year the gloves came off and I decided to sell the JP LMOS and switch to a Rubber City Full Mass BCG and had Craddock Precision build me a custom .308 upper with a 22" Bartlein, 1:11.25 twist with their heavy profile.

It's hard to be a critic with large frame ARs because they're just harder to shoot small groups. The technique is so much more sensitive than small frame, bolt guns, or even 6.5CM AR10. If I haven't spent time on the AR10, the first 20-40 rounds aren't pretty I've noticed that when shooting groups I need quite a bit more rear-ward grip pressure (maybe ~8-10 lbs of pull?) and the fill in my rear bag needs to be settled otherwise I send one high. All things said, I'm happy where my rifle is shooting at today. 2 weeks ago at a Train Up I ran the KYL at 500 yards and was connecting with some 1 to 1.5 MOA targets. The 2 MOA targets were cake. All this said - I spent a shit load of money to get this rifle to shoot. I probably could've bought a GAP-10 and several cases of match ammo for what I spent messing around with parts. I'd say if you decide to roll your own, don't skimp on parts and I'd highly recommend a custom upper from a shop like Craddock Precision.

 

[Longshot85]

Firearms - GAP-10 Gen-1 Long Range Sniper Rifle in 6.5 Creedmoor.

GA-Precision GAP-10 (Early Gen-1) in the Very Popular 6.5 Creedmoor in Like New condition. Round Count is around 400 rounds and it shoots Lights Out Accurate. It features a Heavy 22" Bartlein .875 contour Match Barrel with 1x8.2 Twist and a Badger Thruster Muzzle Brake, Barrel is also Threaded...

www.snipershide.com

A pretty solid ready to rock option.

Like others have said, AR10's are not nearly as easy to build as far as all parts from all manufacturers being compatible.

Wanting a monolithic upper really limits what is available nowadays because as you stated....Mega/Zev isn't accessible nowadays.

I would definitely buy a matching set of upper/lower receivers of high quality.

One thing I've been curious about and maybe some fellow members can answer for both of us.........does any manufacturer of AR10 upper receivers make them "thermo fit" how BCM does ? When I built my precision AR15 I used a BCM upper and also used Loctite 409 to install my WOA SPR barrel......between those things and the rest of the build .....it hammers 0.5 -0.75 MOA with factory ammo.

 

[JohnDeereGuy1996]

Buy an sp10, Lmt or Kac and be done. I built a 243 last year for my thermal coyote rig out of all super nice parts and I’m still dicking with it trying to get it to run like I want.(I know what I’m doing also) just couldn’t find what I wanted in the cal I wanted.

 

[weasle]

Have you tried v Seven??? It's ar10/SR25 style matching set.

V Seven Weapon System
I wish they made the ar10/sr25 with the Li Aluminum...
I believe Sport South now carries Larue's Stuff.
I'm not sure if sport south carries just the larue upper in 308... but that was cheaper than building it out from scatch.

Question...IF the Rail system locks on to the action would you still be concerned about the bipod putting pressure on the barrel nut?

I'm assuming your matching sr25/sr25 style uppers (SR25 style vs DPMS style)

 

[BurtG]

I’d buy a GAP10 , Seekins or try a Sgt arms

Rifles | Texas | Sgt. of Arms

This page will have every line of rifle we offer. From Ar10 to Ar15 rifles in every configuration. We offer standard first time buyer type rifles all the way to full blown competition rifles. Don't see exactly what you want? We do full custom builds to fit the customers exact needs.

www.sgtofarms.com

I have a Seekins I had a proof cf 65cm barrel put in. Insanely accurate.

 

[Longshot85]

@SolidCopper not to sound like a broken record but I cannot state enough how different AR10's are vs AR15 as far as assembling one that hammers 0.75 moa or better. I built a 16 in 6.5CM AR10.....life happened and i haven't had time to even test fire it once. I am expecting several headaches to have to troubleshoot.

If you don't want to be f*$king around with it AND you want accuracy.....buy one of the suggested known solid options.

 

[BCP]

Gents, I have been scouring the forum for info and I'm stuck in a feedback loop in my head. I want to put together a precision gas gun in .308 (because I have access to the ammo). This would be for range use, primarily, but I like to build duty-quality/reliability rifles. I had settled on Seekins builder sets for receivers/forearm because you minimize/eliminate the pressure on the barrel nut when you run the rifle on a bipod. I've discovered that they are very hard to find and expensive as hell when you do find them. My questions are these:

If not Seekins, whose upper/forearm combo is best for elimination of the input into the barrel when using a bipod? I love the direct forearm-receiver attachment but Seekins, Mega/ZEV, etc don't seem to be obtainable any more. I wish Larue had a large-frame builders set.

Am I going to spend as much money building one of these as I am buying something outright from JP (highly recommended) or an SP10 from Seekins?

I've been following @Bigjake83's posts regarding small frame precision rifle building and have used his formula to put a dandy small frame recce rifle together. I'd like to try it with a large frame.

Any input? Am I just spinning my wheels?

Thanks for your time.

I highly suggest buying something like an LMT, Seekins, maybe a Larue if you find a used one that's a proven shooter

Building isn't hard but you're beholden to parts availability and oftentimes you simply cannot find the stuff you want w/o waiting for months on a backorder

 

[BurtG]

Ooh Larue obr with the good barrel.

That would be a cool one for sure

Marks a dbag but some of his rifles are nice

 

[SolidCopper]

Have you tried v Seven??? It's ar10/SR25 style matching set.

V Seven Weapon System
I wish they made the ar10/sr25 with the Li Aluminum...
I believe Sport South now carries Larue's Stuff.
I'm not sure if sport south carries just the larue upper in 308... but that was cheaper than building it out from scatch.

Question...IF the Rail system locks on to the action would you still be concerned about the bipod putting pressure on the barrel nut?

I haven't looked at V7 but I'll look. My intention with a rail/receiver joint is to remove the barrel nut from the equation. I am assigned a Wilson AR10 at work. It employs a standard rail/barrel nut attachment system and I find that if I load the bipod wrong or put too much downward pressure on the buttstock with my face, I get unacceptable POI shift. I have taken to shooting it off my pack and sliding the rifle forward so that the magwell touches the pack. This has solved my work rifle issue and it's a laser when I remember to hyper focus on my fundamentals.

 

[Chickentoast]

I haven't looked at V7 but I'll look. My intention with a rail/receiver joint is to remove the barrel nut from the equation. I am assigned a Wilson AR10 at work. It employs a standard rail/barrel nut attachment system and I find that if I load the bipod wrong or put too much downward pressure on the buttstock with my face, I get unacceptable POI shift. I have taken to shooting it off my pack and sliding the rifle forward so that the magwell touches the pack. This has solved my work rifle issue and it's a laser when I remember to hyper focus on my fundamentals.

I used V7 stuff on my small and large frame builds. It's very high quality, but more for lightweight builds. I think you have the right idea with the SP10 style of lockup for a range beast that can maximize the potential of the cartridge.

 

[LRRPF52]

The two GAP-built AR-10s I had them custom do for me are two of the most accurate AR-10s I’ve shot.

First one was .308 with an Obermeyer barrel, point and click rifle that was a joy to shoot.

Second was a .260 Rem Bartlein that is a laser at distance, first groups I shot with it were 5rds into .75”, then they just kept shrinking into the .4s, 5rds. Loves 139gr Scenars, 142gr SMKs, 130gr Berger VLDs, and the Hornady 130gr ELD-M Match ammo.

Best thing is they also run, unlike a lot of guns out there in the large frame world. My original 24” ArmaLite AR-10 was a laser too, with the M14 type mags.

I have a Savage MSR-10 small frame AR-10 in .308 that I think would make a better base action to work with, since it feels and handles like a med/heavy AR-15. It has a chromed bolt carrier with tower, instead of a carrier key. Adjustable gas, fluted, semi-monolithic upper receiver, 2-stage trigger, etc.

I’m not fond of the brick-like large frame receivers.

 

[LRRPF52]

After all these years messing with large frames, I think I would buy a Savage MSR-10, see if it shoots.

If it didn’t, I would send it to a reputable smith and have them pimp it out with a Bartlein pipe.

Cerakote it in something FDE or RAL8000, grip of choice, etc.

The handguard is already done on it though, no need to mess with it as it doesn’t touch the barrel nut at all.

 

[BurtG]

not fond of the brick-like large frame receivers.

Zactly think that’s why everyone’s all over 6arc

 

[SolidCopper]

After all these years messing with large frames, I think I would buy a Savage MSR-10, see if it shoots.

If it didn’t, I would send it to a reputable smith and have them pimp it out with a Bartlein pipe.

Cerakote it in something FDE or RAL8000, grip of choice, etc.

The handguard is already done on it though, no need to mess with it as it doesn’t touch the barrel nut at all.

Interesting. My impression of savage rifles is that they are the ugly duckling of the reasonably-accurate rifle world. I'm not familiar with this rifle and will look at it.

Seems like the consensus is, "buy a nice one."

 

[XP1K]

Somebody recommending a savage on the Hide? Hell has frozen over. All jokes aside, that's actually a decent looking rifle.

My large frame journey started with sig, then pos, I mean pof, then I built a di out of the pof receivers, then turned it back to its original self and sold it. Then I picked up a pws, loved it, shot awesome, then I sold it because I got an awesome deal on a like new lmt, been happy with that decision ever since.

The sad part is I really wanted an lmt from the get go but the sig caught my eye at a gunshow and I bought it instead. Only to come full circle and end up with an lmt 6k dollars later.

The lmt has been the most consistent shooter of them all for me yet. My pws was a hammer and I really struggled with letting it go. I sold it to someone close with the caveat I would trade them the lmt straight up to get it back if it didn't shoot as good as I wanted it to. So far, it has surpassed all my expectations.

 

[BurtG]

mean pof, t

They were / are some of the most accurate rifles around. My 556s and 762 are accurate af


Frank says :

 

[XP1K]

They were / are some of the most accurate rifles around. My 556s and 762 are accurate af


Frank says :
View attachment 8645309

I had read a lot of good things about them before I purchased the one I had. Researching semi autos is actually what led me to the hide.

Mine just wouldn't consistently shoot well at all. It could be awesome one day, then shoot 3 moa the next. That was the only large frame I ever had that I had that issue with.

 

[LRRPF52]

Somebody recommending a savage on the Hide? Hell has frozen over. All jokes aside, that's actually a decent looking rifle.

My large frame journey started with sig, then pos, I mean pof, then I built a di out of the pof receivers, then turned it back to its original self and sold it. Then I picked up a pws, loved it, shot awesome, then I sold it because I got an awesome deal on a like new lmt, been happy with that decision ever since.

The sad part is I really wanted an lmt from the get go but the sig caught my eye at a gunshow and I bought it instead. Only to come full circle and end up with an lmt 6k dollars later.

The lmt has been the most consistent shooter of them all for me yet. My pws was a hammer and I really struggled with letting it go. I sold it to someone close with the caveat I would trade them the lmt straight up to get it back if it didn't shoot as good as I wanted it to. So far, it has surpassed all my expectations.

Yeah, the MSR-10s don’t look, feel, or have finishes anything like Savage bolt guns.

Totally different rifle fit/feel/finish.

The mechanical advantage adjustable gas isn’t limited in turns either. I disassembled mine to take a closer look at it and discovered that about the gas block. It has a locking seal feature on the gas tube to gas block fit as well, reminiscent of the SASS program.

If mine doesn’t shoot, I’m going to have a 7mm SWC barrel spun up for it, and use the factory gas block if I can.

My friend’s 6.5CM MSR-10 bug-holes out of the box with Hornady 147gr ELD-M if I recall. He was shocked at how accurate it was. He’s a big benchrest guy who has his own portable press, loads for 6 PPC right there on the range.

I panic-bought my MSR-10 .308 during COVID. Weird things happen when you’ve been panic-buying since 1987, and you layer stages of panic-buying on top of decades of it.

 

[BigGameJames87]

OP I was in the same boat as you in regards to trying to find a Seekins builders kit. I ended up just buying an SP10 on a Black Friday sale through Eurooptic and using the savings to fund upgrades. I picked up the gun, an upgraded trigger, different gas block, and a brake all for what the gun normally cost. It was on backorder so I didn't get it until last week but so far it shoots well.

 

[BCP]

I had read a lot of good things about them before I purchased the one I had. Researching semi autos is actually what led me to the hide.

Mine just wouldn't consistently shoot well at all. It could be awesome one day, then shoot 3 moa the next. That was the only large frame I ever had that I had that issue with.

I had a similar experience with two 20" POF rifles they just didn't shoot consistently.

My 716i handles and runs a lot better although groups are mediocre, 2-3MOA, 1.5MOA with handloads.

OP I was in the same boat as you in regards to trying to find a Seekins builders kit. I ended up just buying an SP10 on a Black Friday sale through Eurooptic and using the savings to fund upgrades. I picked up the gun, an upgraded trigger, different gas block, and a brake all for what the gun normally cost. It was on backorder so I didn't get it until last week but so far it shoots well.

Primary Arms had some larue 308s for 2500 not too long ago they were old style OBRs, probably fluted barrel but my PredatAR ran fine no problem with handloading either

 

[nickw]

If you have the scratch, JP, GAP or Craddock is where I’d look. I have a 20” JP 308 and love it. Will probably order a 6.5C upper. We had a GAP .308 gasser at work and it was a hammer. More $ for sure but rifles from these mfg’s shoot. JP is showing a .308 and a few 6.5C rifles in stock. No affiliation. Good luck.

https://www.jprifles.com/buy.php?item=RR-LRP07PRO