General Purpose AR10 Build Critique

[PBWalsh]

Hello,
Looking at a large frame AR to supplement my 12.5” 5.56 AR. This will be my first 308 semi-auto and I want to do it right the first time. Budget is not exactly defined, but I do not want to spend Scar17/SR25 money either. I’ll pay for what I need and save on what I can. Call it 2-2.5k for the rifle itself.

Purpose:
General use carbine from 50-600 yards for when something a bit larger than a 12.5” 5.56 is needed. This is not an ”HD” or “truck” gun. Might see some light hunting use as well. Think large frame recce rifle and it may give a better image of what I’m wanting to do. For reference, if money was no object, I’d get a KAC SR25 CC topped with an NXS 2.5-10x42.

I don’t mind too much tuning, just want it to be able to run 147/150gr and 175/178gr class ammo reliably. Will be ran mostly, if not 100%, suppressed (OSS Helix 762 QD). Would like to see .75-1 MOA with match loads. My 5.56 shoots around that so I expect the same from a large frame once I learn to drive the rifle properly.

With that in mind, my current estimated build list is as follows:

Lower:
Aero M5 Builder Set (with 12” MLOK handguard)
Aero LPK
Trigger Tech Diamond Flat PVD
Radian Ambi safety
Vltor A5 buffer system
Phase 5 EBRVS (BAD Lever)
BCM Mod 1 stock
Magpul ASAP end plate
BCM/MK Machine Grip

Upper:
Criterion (38oz) or Faxon Barrel (32oz)
Aero/SLR Gas Tube
Aero/SLR Gas Block
OSS 762 Flash Suppressor (already have an OSS Helix 762 QD)
Radian Raptor SD charging handle
JP FMOS BCG

What parts do I need to consider changing or alternatives to consider? Specifically interested in the opinion of Faxon barrels. Yes I know a 6.5CM beats a 308, but I can’t buy surplus 6.5.

Besides an AR10 reaction rod, is there any other specialized tools I’ll need for assembly? I’ve got anything I could reasonably need for small frames.

Anyways, suggestions, pictures, and comments are always welcome.

Tagging in a few folks who I think may have some experience in this area:
@MSTN
@bigjake83
@padom

Thanks,
PBWalsh

 

[padom]

Looks decent. I'm not a Aero receiver/handguard fan. Mega or seekins for me all day. Too many issues over the years with out of spec parts and horrible customer experience and excuses...

I'd hit the easy button on the barrel if not going custom Bartlein/Krieger from Keystone Accuracy, Compass Lake, Craddock.....get a 308 from Wilson combat. I've had many and they shoot great and are affordable.

Order right now, everything is on sale for black friday....fluted, whatever you want

Rifle - Magazines - Accessories

shopwilsoncombat.com

I used AGB for years. But I won't go that route again. The past 1year+ I've switched over to using Rubber City Adjustable Gas Key BCG's eith a Geissele super gas block.

Standard Mass AR-10 .308 Win+ Multi HP Calibers DPMS complete W/ Assist & Adjustable Gas Key - Welcome to Rubber City Armory

This is a complete AR-10/SR-25 DPMS style BCG with Blacknitride+ finish Carrier is fluted WITH FORWARD ASSIST and incorporates RCA's ADJUSTABLE billet gas key Bolt face is specifically machined to handle high pressure rounds. The firing pin is custom matched to this firing pin hole. Caliber...

rubbercityarmory.com

These RCA adjustable gas key bcgs are the rage. Took a minute to tuned then your done. No carbon locking gas blocks anymore like I've dealt with for yours. I actually built a 308 Krieger AR upper last year with one and love it.

 

[PBWalsh]

Any meaningful difference between the Seekins/Mega/Zev/SLR receiver or builder sets?

 

[Bigjake83]

Any meaningful difference between the Seekins/Mega/Zev/SLR receiver or builder sets?

Mega/Zev/and SLR are all the same design and really can't go wrong with either but the Seekins has the newer style upper receiver where the barrel nut is not attach the handguard which in my opinion tends to produce greater accuracy.

As far as tools go, a reaction rod and a torque wrench are about all you need.

I think you're definitely heading in the right direction but I would save a few more bucks and get a quality Barrel, your Barrel is the heart of your rifle so if you're going to do anything do that one 100% right.

 

[Bigjake83]

If I was in your shoes and didn't want to pay big money, I would watch the marketplace and see if you can stumble across an Seekins SP10. In .308

Another option is a LaRue Large frame UU kit, I see them come up for sale all the time on AR15.com they are lighter and generally cheaper than the SP10.

The LaRue UU kits are a good option for somebody cutting their teeth on their first build, the UU kits fit too loose on the LaRue lowers in my opinion but I can show you how to permanently fix that in about 30 minutes.

I found a build that somebody is selling on AR15.com that has a quality parts list and looks exactly what you're looking for for $1200. If you're interested send me a message and I'll send you the link.

 

[db2000]

Seekins is near monolithic. They’re back ordered almost a year in reality despite what they may quote you fyi. I still vote Seekins. You have to be careful Frankensteining large frame AR.

I have a Phase V .308 release for sale fyi.
*edit
This is for sale in the PX.

 

[the monk]

I agree with @padom, I personally would get a much better barrel. The foundation of the AR platform is the barrel, BCG, and trigger. Looks like you are gtg on the BCG and trigger. Only thing that gives me pause is the barrel. There are so many great barrel makers out there. Spend the money, there is a difference.

I would personally ditch the Phase 5 EBRVS. Its a 308, you are not banging out speed. Or at least install it after you have fully vetted the build.

 

[db2000]

I agree with @padom, I personally would get a much better barrel. The foundation of the AR platform is the barrel, BCG, and trigger. Looks like you are gtg on the BCG and trigger. Only thing that gives me pause is the barrel. There are so many great barrel makers out there. Spend the money, there is a difference.

I would personally ditch the Phase 5 EBRVS. Its a 308, you are not banging out speed. Or at least install it after you have fully vetted the build.

Really? Ditch convenience

 

[RUTGERS95]

Hello,
Looking at a large frame AR to supplement my 12.5” 5.56 AR. This will be my first 308 semi-auto and I want to do it right the first time. Budget is not exactly defined, but I do not want to spend Scar17/SR25 money either. I’ll pay for what I need and save on what I can. Call it 2-2.5k for the rifle itself.

Purpose:
General use carbine from 50-600 yards for when something a bit larger than a 12.5” 5.56 is needed. This is not an ”HD” or “truck” gun. Might see some light hunting use as well. Think large frame recce rifle and it may give a better image of what I’m wanting to do. For reference, if money was no object, I’d get a KAC SR25 CC topped with an NXS 2.5-10x42.

I don’t mind too much tuning, just want it to be able to run 147/150gr and 175/178gr class ammo reliably. Will be ran mostly, if not 100%, suppressed (OSS Helix 762 QD). Would like to see .75-1 MOA with match loads. My 5.56 shoots around that so I expect the same from a large frame once I learn to drive the rifle properly.

With that in mind, my current estimated build list is as follows:

Lower:
Aero M5 Builder Set (with 12” MLOK handguard)
Aero LPK
Trigger Tech Diamond Flat PVD
Radian Ambi safety
Vltor A5 buffer system
Phase 5 EBRVS (BAD Lever)
BCM Mod 1 stock
Magpul ASAP end plate
BCM/MK Machine Grip

Upper:
Criterion (38oz) or Faxon Barrel (32oz)
Aero/SLR Gas Tube
Aero/SLR Gas Block
OSS 762 Flash Suppressor (already have an OSS Helix 762 QD)
Radian Raptor SD charging handle
JP FMOS BCG

What parts do I need to consider changing or alternatives to consider? Specifically interested in the opinion of Faxon barrels. Yes I know a 6.5CM beats a 308, but I can’t buy surplus 6.5.

Besides an AR10 reaction rod, is there any other specialized tools I’ll need for assembly? I’ve got anything I could reasonably need for small frames.

Anyways, suggestions, pictures, and comments are always welcome.

Tagging in a few folks who I think may have some experience in this area:
@MSTN
@bigjake83
@padom

Thanks,
PBWalsh

Better off buying a complete Aero Lower and Upper and swapping the barrel to the criterion if needed but based on what you spec'd and requirements, simply buying the complete lower and lower would be best bet. Aero is fantastic for builds or for keeping the price lower. zero reason to spend more based on your criteria. You won't get anything over the BA barrel with a Faxon barrel imho

 

[MSTN]

I've only used a fraction of the parts you list. I'll comment on what I know - or what I THINK I know.

In a 16" barrel, intermediate gas is the way to go. I don't build longer in .308.

Grips and stocks tend to be personal choices. I myself like the BCM stock and grip - but there are lots of other solid choices out there. I still use the same pistol grip from Sierra Precision Rifle I started using 25 years ago.

You can use the Vltor A5 lower receiver extension (same as .308 carbine length), but you'll need the correct buffer and recoil spring for a .308 caliber.

I'm a big TriggerTech fan - But I personally don't like to go less than the 2.5 LB trigger in the TriggerTech Adaptable trigger module in a weapon of this format. Too much chance of bump firing in weird positions.

In the .308, I find the JP LMOS with SLR adjustable gas block plus JP recoil spring and H2 buffer gives reliable, accurate performance with an amazingly low recoil pulse. The OSS Brake is pretty effective, too. This combo works so well I've quit looking at alternatives.

The SP10 Builder's Kit will produce a really rigid barrel support. But, it won't be the lightest way to go. I've had great luck with them in terms of accuracy.

The LaRue stuff, in my experience, is simply tough to beat in a big block gun. My old LaRue .260 with original 2016 vintage Swedish made Prime 130 is the most accurate gas gun I've ever owned. I can't top it. Yes, it does piss me off a little.

 

[PBWalsh]

Thanks y’all.

Not able to buy right now, 2022 is when this would be slated for building, if I do actually do it.

Really liking the Wilson Combat Ranger profile @padom linked. I guess I like the Criterion/Faxon offering due to the chromed/nitrided barrel compared to straight stainless offerings. Not that this will be a super high round count gun though, estimating ~1-1.5k rounds per year.

Weight is a high concern here, hoping to keep it under 12lbs with a 19.7oz suppressor. Base gun should be <9lbs. Again, not needing a gun to compete in the PRS gas gun division where, just something that delivers more KE than what an AR15 can deliver.

@bigjake83 the SP10 is close, except for the barrel. The weight of that rifle is counter to my use. If weight didn’t matter, I’d probably go with it.

Please keep up suggestions, writing all this down on a parts list spreadsheet.

 

[Harman117]

I would be sure to use the Enhanced Aero M5E1 upper with their handguard. Uses a similar concept as the the Seekins upper with the integral handguard mounting interface. (Mega (Zev) also has a version of this if you really wanted to blow money)

Aero M5E1 ENHANCED:

Any extra weight from a system like this is probably pretty minimal and definitely worth it IMO.

But overall I would not spend the extra money for a Seekins/Mega if you have a strict budget. Instead dump any extra money into the barrel like previously said. You'd be hard pressed to find an actual difference in performance between these receiver sets anyways. The barrel however is a different story... (Sgt of Arms didn't have any issues winning the 2020 PRS Gas division using Aero M5E1 Enhanced uppers)

 

[db2000]

I would be sure to use the Enhanced Aero M5E1 upper with their handguard. Uses a similar concept as the the Seekins upper with the integral handguard mounting interface. (Mega (Zev) also has a version of this if you really wanted to blow money)

Aero M5E1 ENHANCED:
View attachment 7748632

Any extra weight from a system like this is probably pretty minimal and definitely worth it IMO.

But overall I would not spend the extra money for a Seekins/Mega if you have a strict budget. Instead dump any extra money into the barrel like previously said. You'd be hard pressed to find an actual difference in performance between these receiver sets anyways. The barrel however is a different story... (Sgt of Arms didn't have any issues winning the 2020 PRS Gas division using Aero M5E1 Enhanced uppers)

Wow. Didn’t realize they made this. Sounds like good advice.

 

[_Windrider_]

Honestly just buy an SP10 or DD or something. Your gonna spend that money anyway. Save yourself a lot of headache if it’s your first foray into an AR10.

 

[Harman117]

Wow. Didn’t realize they made this. Sounds like good advice.

They're pretty nice especially for the price. (Like half of the next closest competitor's)

I should also clarify Sgt of Arms may do additional procedures when they build their Aero uppers, I don't know.

Edit: you could also buy a complete rifle from Sgt of Arms if you wanted. They probably have a build/model that meets your specs.

 

[PBWalsh]

Honestly just buy an SP10 or DD or something. Your gonna spend that money anyway. Save yourself a lot of headache if it’s your first foray into an AR10.

Again, the SP10 is 10.3lbs. If weight didn’t matter I‘d definitely consider one.

 

[Hkmiller]

Hello,
Looking at a large frame AR to supplement my 12.5” 5.56 AR. This will be my first 308 semi-auto and I want to do it right the first time. Budget is not exactly defined, but I do not want to spend Scar17/SR25 money either. I’ll pay for what I need and save on what I can. Call it 2-2.5k for the rifle itself.

Purpose:
General use carbine from 50-600 yards for when something a bit larger than a 12.5” 5.56 is needed. This is not an ”HD” or “truck” gun. Might see some light hunting use as well. Think large frame recce rifle and it may give a better image of what I’m wanting to do. For reference, if money was no object, I’d get a KAC SR25 CC topped with an NXS 2.5-10x42.

I don’t mind too much tuning, just want it to be able to run 147/150gr and 175/178gr class ammo reliably. Will be ran mostly, if not 100%, suppressed (OSS Helix 762 QD). Would like to see .75-1 MOA with match loads. My 5.56 shoots around that so I expect the same from a large frame once I learn to drive the rifle properly.

With that in mind, my current estimated build list is as follows:

Lower:
Aero M5 Builder Set (with 12” MLOK handguard)
Aero LPK
Trigger Tech Diamond Flat PVD
Radian Ambi safety
Vltor A5 buffer system
Phase 5 EBRVS (BAD Lever)
BCM Mod 1 stock
Magpul ASAP end plate
BCM/MK Machine Grip

Upper:
Criterion (38oz) or Faxon Barrel (32oz)
Aero/SLR Gas Tube
Aero/SLR Gas Block
OSS 762 Flash Suppressor (already have an OSS Helix 762 QD)
Radian Raptor SD charging handle
JP FMOS BCG

What parts do I need to consider changing or alternatives to consider? Specifically interested in the opinion of Faxon barrels. Yes I know a 6.5CM beats a 308, but I can’t buy surplus 6.5.

Besides an AR10 reaction rod, is there any other specialized tools I’ll need for assembly? I’ve got anything I could reasonably need for small frames.

Anyways, suggestions, pictures, and comments are always welcome.

Tagging in a few folks who I think may have some experience in this area:
@MSTN
@bigjake83
@padom

Thanks,
PBWalsh

I have a criterion/fulton armory match 18.5" in. 308. Shoots 1/4 to 1/2 MOA with my reloads. Shot factory Remington 180 core-lokt today 1/2 MOA.

 

[blbennett1288]

I agree with @TacticalDillhole

The AR10 is a lot less plug and play than an AR15 and mixing and matching different manufactures components might not always work or if they do work might not lead to the best results.

Personally if it was my money I would buy a complete system and change out the components I prioritized first. That way you have a baseline to return to if things don’t work out well.

 

[padom]

I have a criterion/fulton armory match 18.5" in. 308. Shoots 1/4 to 1/2 MOA with my reloads. Shot factory Remington 180 core-lokt today 1/2 MOA.

No gasser is shooting 1/4 to 1/2moa. Come on man. We've been doing this a long time. What is that picture showing us????

I see 2 holes circled on a piece of paper. You can even tell me that's 3. Doesn't make a barrel a 1/4moa barrel.lolol Show me a 5x5 or a 6x5 agg of .25 - .5....

 

[r.tenorio671]

...weight & price seem to be your primary considerations, here's another barrel option. FWIW all of my BA barrels are accurate with general purpose ammo, more so with FGGM (which I use for initial testing & baseline data) & my handloads...

18

Extra weight helps your barrel shoot off hand more easily. This 18 inch heavy profile 308 Winchester barrel is the perfect way to achieve this goal.

www.ballisticadvantage.com

...FWIW, I have been using SLR AGB's exclusively for over 10 years, since their Gen 1 days w/556, 300BO, 6.5CM and .308 and have never experienced carbon lock to date. After I use a rifle and before I put it away I just open the adjustment fully, close fully and repeat maybe 2-3 times to "auger" off any carbon accumulation then return to it's normal setting, G2G. Soon to be using one with my 6ARC build. YMMV

 

[Hkmiller]

No gasser is shooting 1/4 to 1/2moa. Come on man. We've been doing this a long time. What is that picture showing us????

I see 2 holes circled on a piece of paper. You can even tell me that's 3. Doesn't make a barrel a 1/4moa barrel.lolol Show me a 5x5 or a 6x5 agg of .25 - .5....

Here's a better one five shots at a hundred yards.

 

[padom]

Here's a better one five shots at a hundred yards.

Lol. What are you trying to say? Are you still claiming a 1/4moa gasser?

 

[gixxer822]

Aero receivers are gtg. They have small feed ramps which some AR/LR308s don’t. JP bolt is a must imo. Even with 308 I’m still blowing primers occasionally with standard bolt. Faxon makes a decent rail also. I prefer it over the non enhanced aero rails. It won’t need shims or clocking like some aero rails. Also, Aeros gas blocks have more adjustment then they claim. My GB needs 17 clicks to be wide open

 

[Hkmiller]

Lol. What are you trying to say? Are you still claiming a 1/4moa gasser?

I'll let you do the math on that.

What groups do you get with your gasser?

 

[padom]

I'll let you do the math on that.

What groups do you get with your gasser?

You have a lot to learn. I'll leave it at that

Do some research around here, you'll see what groups I get with all my gassers.....I don't post single groups and make outlandish claims though.. hahah

 

[Hkmiller]

You have a lot to learn. I'll leave it at that

Do some research around here, you'll see what groups I get with all my gassers.....I don't post single groups and make outlandish claims though.. hahah

Hey I appreciate your your reply on that you probably have a lot to learn too. The sign of a smart mind is you're always learning. You might be an expert in shooting which I enjoy it I'm not claiming to be an expert so say what you want do what you want.
Show me your groups.

 

[RickyRodney]

I've only used a fraction of the parts you list. I'll comment on what I know - or what I THINK I know.

In a 16" barrel, intermediate gas is the way to go. I don't build longer in .308.

Grips and stocks tend to be personal choices. I myself like the BCM stock and grip - but there are lots of other solid choices out there. I still use the same pistol grip from Sierra Precision Rifle I started using 25 years ago.

You can use the Vltor A5 lower receiver extension (same as .308 carbine length), but you'll need the correct buffer and recoil spring for a .308 caliber.

I'm a big TriggerTech fan - But I personally don't like to go less than the 2.5 LB trigger in the TriggerTech Adaptable trigger module in a weapon of this format. Too much chance of bump firing in weird positions.

In the .308, I find the JP LMOS with SLR adjustable gas block plus JP recoil spring and H2 buffer gives reliable, accurate performance with an amazingly low recoil pulse. The OSS Brake is pretty effective, too. This combo works so well I've quit looking at alternatives.

The SP10 Builder's Kit will produce a really rigid barrel support. But, it won't be the lightest way to go. I've had great luck with them in terms of accuracy.

The LaRue stuff, in my experience, is simply tough to beat in a big block gun. My old LaRue .260 with original 2016 vintage Swedish made Prime 130 is the most accurate gas gun I've ever owned. I can't top it. Yes, it does piss me off a little.

When you say JP recoil spring, are you specifically referring to their recoil spring and H2 or the silent capture system. May seem like a stupid question but I have heard great things about the silent capture set-up.

Also to the OP - If you REALLY want an off the shelf barrel my friends proof barrel is an absolute hammer, its a sample of 1 barrel but just his experience.

 

[KYAggie]

Here’s some light, no pun intended, reading for you. I later completed a 16” barreled 308 that weights 6# unloaded. It’s a dream to carry and to shoot as it weights the same as many AR15’s. It is possible to build these things light if you are mindful of what all the parts weigh. I was enjoying my M1A’s and saw no reason to get into AR10‘s until I found out how light you can build one and how reliable they can be if you understand how they work. Good luck with your project and PM me if you have questions.

Lightweight 2A Arms Xanthos 6.5 CM Build

First, I want to say this is ALL Breastroker’s fault on M14forum. I had not given the AR10 platform the slightest look of interest because they are as heavy as the M14/M1A and they are not standardized as far as parts go; why bother was how I saw it, so I continued playing with the M14/M1A...

www.snipershide.com

 

[KYAggie]

Here‘s some pictures. This picture showing 123 oz, which is 7.68 pounds, is with a Super Sniper 1-6 scope which with the Aero mount weights 25.8 ounces. The gun weight without scope is 6.075 pounds.

 

[KYAggie]

How does it shoot? Here’s a 5 shot group with 1982 Malaysian surplus circled in blue. The other shots were me messing with the scope adjustments. I’ve never had surplus shoot this good in any gun.

 

[KYAggie]

I then put a Area419 Hellfire brake on it after having my can modified by Ecco Machine. I did a test to see how repeatable the zero is swapping between the brake and can. I found out I needed to make a 1.3 MRAD adjustment to the scope to get the rounds in the same group. In this picture, I fired one shot with the brake on, took the brake off, put the can on, adjusted the scope up 1.3 MRAD, too a shot, took the can off, put the brake on, adjusted the scope down 1.3 MRAD, took a shot, and repeated for 7 total shots. The ammo was 168 FGMM. The 7 shots are circled in blue. The group speaks for itself. These groups were shot at 100 yards with a 1-6 Super Sniper scope.

It is possible to build accurate lightweight AR10’s. This 308 has a Faxon gunner weight 16” barrel.

 

[MSTN]

I've used both the JP recoil spring and the SCS. I can't see a difference in performance, and the former is less $$$.

I have a significant hearing loss and I don't notice any noise.

 

[r.tenorio671]

....I always use commercial type ammo thru any new build for it's first firing to "proof it" and to (1) gather baseline data and (2) set up my AGB's for reliable functioning. I tweak the AGB setting, if needed, for my handloads to a setting that will function with both commercial & handloads. The attached is from testing the accuracy of my selected handload combo against the FGGM. I always click my scope 1 or 2 off so that my aimpoint remains unobscured. The FGGM is only 3-shot, the HDY 155 BTHP is a 10-shot group, all fired off a hasty rest. Build is Aero M5 upper, lower (both blems bought at separate times), Aero LPK, Geissele G2S trigger, Aero standard AR10 carbine buffer/spring/tube and SLR Sentry 7 AGB on a Ballistic Advantage 16" Hanson. This is my GenPurpose large format carbine that is reliable and more than sufficiently accurate.

 

[Hkmiller]

....I always use commercial type ammo thru any new build for it's first firing to "proof it" and to (1) gather baseline data and (2) set up my AGB's for reliable functioning. I tweak the AGB setting, if needed, for my handloads to a setting that will function with both commercial & handloads. The attached is from testing the accuracy of my selected handload combo against the FGGM. I always click my scope 1 or 2 off so that my aimpoint remains unobscured. The FGGM is only 3-shot, the HDY 155 BTHP is a 10-shot group, all fired off a hasty rest. Build is Aero M5 upper, lower (both blems bought at separate times), Aero LPK, Geissele G2S trigger, Aero standard AR10 carbine buffer/spring/tube and SLR Sentry 7 AGB on a Ballistic Advantage 16" Hanson. This is my GenPurpose large format carbine that is reliable and more than sufficiently accurate.

Do you get different precision with different setting on you AGB? I have the same AGB.

 

[r.tenorio671]

Do you get different precision with different setting on you AGB? I have the same AGB.

...I haven't seen an appreciable difference per se. Any adjustments that have to be made are usually related to changes in powder brand and charge weight used for my handloads, but a component change automatically means load development verification, for me at least. When I'm able to buy powder, I prefer 8# jugs but if only 1# cans, try to get the case of 10 cans so they will be from same lot (usually). With commercial ammo, only difference I've seen was due to the "age" of the ammo if it was more than 3-5 years old and had to do with effect on functional operation (cycling). I'm no longer obsessed with extreme accuracy in my AR's, "minute of man" at a minimum is good enough for me...100% reliable function is more important as reinforced by one of Uncle Sam's "vacation getaways", LOL.

...it is possible to get accuracy/precision out of AR's, there are many on this board that do. Like any platform, you can go for specialization or multi-role, each gives up on some areas to increase others, it's a balancing act only the individual can determine.

 

[sea2summit]

I have a criterion/fulton armory match 18.5" in. 308. Shoots 1/4 to 1/2 MOA with my reloads. Shot factory Remington 180 core-lokt today 1/2 MOA.

Lol.

Yes you have two holes that appear to be with 1/2 MOA. You are not shooting consistently sub 1/2 MOA, and you sure the hell aren’t shooting 1/4 MOA very often with five rounds.

 

[sea2summit]

Here's a better one five shots at a hundred yards.

That’s not 1/4 MOA.

 

[sea2summit]

I'll let you do the math on that.

What groups do you get with your gasser

Best 5x5 I have a picture of. My smallest looks a lot like the one you want us to do math on.

 

[sea2summit]

OP, only thing I’d really change in your build is the charging handle, I like the gas buster.

Someone said LT UU kit, I have a ton of LT rifles and no parts I’ve gotten from LT come close to the complete rifles. Having said that, since their prices are literally crazy now I would spend the same money elsewhere. Think you could do a GAP-10 for what LT wants now.

 

[Daddyusmaximus]

I don't have my .308 AR anymore, and I kinda wish I did. I built it as a general use carbine that wasn't too big to be carried as a primary weapon if it came down to it. It would give me more juice than my 5.56, but Was still compact, (for a .308) as long distance wasn't the goal. I went with a 14" Ballistic Advantage barrel they had on sale because they were discontinuing it. With a Warcomp pin & welded, it hit the government's magical 16", so they were happy. I'd love to build another like it, but at today's prices, and with no .308 ammo anymore... it wouldn't be practical to jump back into the .308 game. I don't remember reading exactly what your overall goal was, but to me, a handy little multi-use carbine is the way to go.

 

[PBWalsh]

I don't have my .308 AR anymore, and I kinda wish I did. I built it as a general use carbine that wasn't too big to be carried as a primary weapon if it came down to it. It would give me more juice than my 5.56, but Was still compact, (for a .308) as long distance wasn't the goal. I went with a 14" Ballistic Advantage barrel they had on sale because they were discontinuing it. With a Warcomp pin & welded, it hit the government's magical 16", so they were happy. I'd love to build another like it, but at today's prices, and with no .308 ammo anymore... it wouldn't be practical to jump back into the .308 game. I don't remember reading exactly what your overall goal was, but to me, a handy little multi-use carbine is the way to go.

View attachment 7753318

This is basically what I'm after, a rifle with more kinetic energy at distance than an AR15 will allow while also being light enough to fulfil a general purpose carbine role.

Do you remember the weight and accuracy of this rifle? What was your reason to go with the standard Aero M5 receivers and not the enhanced version?

 

[Daddyusmaximus]

Never weighed it. I was shooting about 1.5" groups with it. I did get one group under an inch, but I can't say that would have been the norm. (I did brag about it though at the time) I'm not the best shot, but either I sucked, and it could do better, or it was an average rifle, and I got lucky... don't know. I actually ended up not keeping it long after I finished with it. That's the main reason I'm pissed at myself for getting rid of it. I really think it had a lot of potential. As far as the receivers go... they were what I could find in stock at the time. I don't think fancy receivers really get you anything unless you're building a precision build. The heart of an AR is the barrel, and BCG. It was plenty good enough for a combat carbine... and I kinda miss it, but my 5.56 ARs are also plenty good enough, much lighter too.

 

[RUTGERS95]

I don't have my .308 AR anymore, and I kinda wish I did. I built it as a general use carbine that wasn't too big to be carried as a primary weapon if it came down to it. It would give me more juice than my 5.56, but Was still compact, (for a .308) as long distance wasn't the goal. I went with a 14" Ballistic Advantage barrel they had on sale because they were discontinuing it. With a Warcomp pin & welded, it hit the government's magical 16", so they were happy. I'd love to build another like it, but at today's prices, and with no .308 ammo anymore... it wouldn't be practical to jump back into the .308 game. I don't remember reading exactly what your overall goal was, but to me, a handy little multi-use carbine is the way to go.

View attachment 7753318

I just did this and will post pics soon enough. I had the barrel cut so that with the brake, it came right to 16". I used mostly aero parts with a kak barrel and centurion rail.

 

[sboone]

Your build list is almost part for part what I did

I have a regular M5 upper in 16" 308 and a M5E1 upper 16" 6.5CM.

Complete M5 carbine lower with magpul SL stock and a K? Grip

Just upgraded to a geissele G2S trigger.

For the upper I'd probably go M5E1 unless you're wanting to really count ounces. The M5E1 upper/handgaurd is about 6 oz heavier than a comparable more traditional M5 upper/handgaurd.

My 6.5CM barrel is a Faxon Big Gunner, dont like it much, pretty average shooter.

My 16" 308 is a Criterion M118LR barrel and it seemes to be a good one, recommended.

JP LMOS carrier with a HP bolt saves alot of headaches and is very nice.

The JP silent capture spring is worth the upgrade, get it.

SLR sentry detent gas block is pretty low profile but can be a PITA to get to. I like it more than the JP detent block. Theres a new AGB on the market that's being pushed by influencers, dont remember what it's called but it looks easy to use and no tools for adjustment.

The whole package with a Strike eagle 1-8, OSS 762, and 25 round M118 magpul mag is a hair under 13lbs.
Very manageable recoil, a child can, and has (my 6yo), shot it.

 

[r.tenorio671]

SLR sentry detent gas block is pretty low profile but can be a PITA to get to. I like it more than the JP detent block. Theres a new AGB on the market that's being pushed by influencers, dont remember what it's called but it looks easy to use and no tools for adjustment.

....this is true for any front single screw adjuster type of AGB if an overly long handguard is used, which also increases the overall weight of the rifle. For some, the long "look" is appealing and part of the reason they do so. Personally, over a period of time and usage, I forego such, now limiting handguard length so that the adjustment screw is readily accessible and the gas block is fully protected, not to mention weight savings gained.

...attached are images of SLR AGB's in both set screw and clamp models under a CMT UHPR-13.7 MOD 2 HDX handguard. The barrel is my BA 18" 6ARC w/Rifle Length Gas System ordered from Brownell's early in the advent of 6ARC.

Edited: Pics taken during my "mock up" testing of components. The muzzle devices shown are a Brownell's "short .308" compensator (used as a thread/muzzle protector) and a FOSSA-762 flash hider as a possible candidate for a muzzle device. Suppressors are not legal in my locale. YMMV