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So there is a way?
Bluehaze2 recommended x caliber. It's the perfect one tbh considering they make a superlative arms piston specific barrel, and that's the gas system I'm using, but Jesus Christ it's almost $600 for a barrel with like 8 months lead time.
Have you considered the route I took? A road far less traveled. You could use my concept but tweak it in the other direction (for a lightweight 6.8 build). I wanted a heavy barrel without heavy barrel woes (meaning it's so heavy it's tiring, slow to present, front heavy etc.) and to increase overall system performance at the same weight.

So I paired my 16" Daniels S2W CHF CL 5R SPC II barrel with a JL Billet NANO Ultra Magnesium / Aluminum 15" handguard....the handguard with hardware is just 6oz!!! It's lighter weight than carbon fiber handguard setups in that length that clock in at 8oz total. They also make a 13" version that's even lighter yet if you don't need full coverage of a 15".

A standard 6061-T6 15" handguard will run north of 15oz-16oz even with an aluminum barrel nut like the Geissele 13.5" SMR on the SF's new URGI. BCM's 12" m-lock handguard still clocks in at 11oz despite being considerably shorter as well.

So my 16" Heavy barreled 6.8 SPC upper weighs the same as a 16" gov profile 5.56 upper with a standard 15" 6061 T6 m-lok handguard....actually the balance is even better with my setup as more of the total weight is back at the receiver due to the S2W profile and mass bias of the handguard. I've not seen ANYONE explore this concept.

The only use cases I've seen for AZ61A alloy is on ultra lightweight builds where the idea is "light as possible everywhere". No one has used it to off-set the weight of a heavy barrel to make an "standard weight" high performance upper that punches well above it's weight class.

So, what if you paired an ultra lightweight handguard with a standard scout profile 6.8 SPC barrel? That would give you a lightweight 6.8 SPC setup without compromising thermal related accuracy loss associated with pencil barrels and the faster throat erosion that also accompanies those profiles. Throat erosion is directly related to heat, the hotter it gets, the softer the steel and the faster the rate of wear on the lands, the issue is worse with nitrided steel vs. chrome lined.

JL Billet's handguards will fit the SA piston gas system if your bent on that still, but I stand by synopsis to avoid it. I think your better off using DI NiB bolts and NiB carriers in a traditional DI system if your concerned about maintenance time as they are pretty easy to clean and all your going to do is shift the cleaning from the receiver to the gas block / piston assembly.

Short stroke tappet piston setups make the most sense in heavy full auto applications where heat can become a real issue. For a typical infantry AR use, LE or even military, DI with modern plating and good mags is very reliable even if you don't clean it, just keep it wet! BCM ran a mil-spec DI upper for over 30k rounds....not cleaned even once. They just kept dousing it with lube...Fail Zero with their Nib setup has run over 50k rounds through their test upper WITHOUT lube...that's a couple barrels at least...

Here's the weight breakdown difference for illustration (adjusted barrel weight for a 16" gov profile, not the 14.5" used on the actual URGI to give an apples to apples comparison):

URGI (Upper Receiver Group Improved, modified with a 16" gov profile vs. 14.5" gov profile for an apples to apples):
Geissel 13.5" SMR M-Lok Handguard 14.9oz
Daniels 16" Gov profile mid-length 556 Barrel 27.2oz
Total: 42.1oz

6.8 URGHB (Upper Receiver Group Heavy Barrel, this is my implementation):
Handguard 6oz
Barrel 36.9oz
Total: 42.9oz

Difference 0.8oz...and more of that weight is at the back of the receiver where the weight matters a lot less than out front. But I have a barrel in a more powerful caliber and in a heavy profile....my 6.8 URGHB would massively outperform their brand new URGI at nearly the same weight and handling.

6.8 URGSCOUT:
JL Billet NANO Ultra Mag / Alu 15" Handguard 6oz
ARP 16" Scout Barrel 28.6oz
Total: 34.6oz

Or if you pin the gas block AND if ARP still has them:

6.8 URGSCOUT14.5:
JL Billet NANO Ultra Mag / Alu 13" Handguard 5.8oz
ARP 16" Scout Barrel 25oz
Total: 30.8oz...that's a pretty lightweight barrel / handguard config for 6.8 SPC.

Even my 5.56 Daniels Light Weight CHF CL barrel clocks in at 24oz...and that's a pencil profile I use for a training upper / CQB upper for an alternate caliber to my 68 that's a primary.

Gas piston system will also add more weight than a DI gas system, even the SA one (lightest piston system of them all) is 3oz more total weight mostly out front than a low profile gas block (1.3oz) and gas tube (0.6oz) in a DI gas system. Carriers are the same weight. So if your weight conscious, go DI. And this coming from someone who ran AA's also reasonably lightweight piston system for years....

69693

Note that I have since replaced the bulky picatinny mount surefire pressure pad with sure fire's smaller tape version and magpul m-lock mount plate for a lower profile and cleaner design, no rubber bands or zip ties, but at the time of the photo worked reasonably well still, even if a bit ghetto, I was using what I had at the time of the initial build. That's a heavy barreled 6.8 barrel with JL's mag / alum handguard.

Handles like the oh so typical 16" 556 gov profile / 6601 15" m-lok handguard combo but shoots in a league of it's own comparatively.

P.S. sorry for the uber lengthy post, but there was a lot of technical reasoning to my suggestions. I've tried MANY configurations over the last 10 years and I've really honed in on what works and what doesn't, what's the best and what's marginal. I'm always after overmatch, not just in caliber selection, but rifle design, so I roll my own as they say.
 

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Discussion Starter · #22 · (Edited)
Have you considered the route I took? A road far less traveled. You could use my concept but tweak it in the other direction (for a lightweight 6.8 build). I wanted a heavy barrel without heavy barrel woes (meaning it's so heavy it's tiring, slow to present, front heavy etc.) and to increase overall system performance at the same weight.

So I paired my 16" Daniels S2W CHF CL 5R SPC II barrel with a JL Billet NANO Ultra Magnesium / Aluminum 15" handguard....the handguard with hardware is just 6oz!!! It's lighter weight than carbon fiber handguard setups in that length that clock in at 8oz total. They also make a 13" version that's even lighter yet if you don't need full coverage of a 15".

A standard 6061-T6 15" handguard will run north of 15oz-16oz even with an aluminum barrel nut like the Geissele 13.5" SMR on the SF's new URGI. BCM's 12" m-lock handguard still clocks in at 11oz despite being considerably shorter as well.

So my 16" Heavy barreled 6.8 SPC upper weighs the same as a 16" gov profile 5.56 upper with a standard 15" 6061 T6 m-lok handguard....actually the balance is even better with my setup as more of the total weight is back at the receiver due to the S2W profile and mass bias of the handguard. I've not seen ANYONE explore this concept.

The only use cases I've seen for AZ61A alloy is on ultra lightweight builds where the idea is "light as possible everywhere". No one has used it to off-set the weight of a heavy barrel to make an "standard weight" high performance upper that punches well above it's weight class.

So, what if you paired an ultra lightweight handguard with a standard scout profile 6.8 SPC barrel? That would give you a lightweight 6.8 SPC setup without compromising thermal related accuracy loss associated with pencil barrels and the faster throat erosion that also accompanies those profiles. Throat erosion is directly related to heat, the hotter it gets, the softer the steel and the faster the rate of wear on the lands, the issue is worse with nitrided steel vs. chrome lined.

JL Billet's handguards will fit the SA piston gas system if your bent on that still, but I stand by synopsis to avoid it. I think your better off using DI NiB bolts and NiB carriers in a traditional DI system if your concerned about maintenance time as they are pretty easy to clean and all your going to do is shift the cleaning from the receiver to the gas block / piston assembly.

Short stroke tappet piston setups make the most sense in heavy full auto applications where heat can become a real issue. For a typical infantry AR use, LE or even military, DI with modern plating and good mags is very reliable even if you don't clean it, just keep it wet! BCM ran a mil-spec DI upper for over 30k rounds....not cleaned even once. They just kept dousing it with lube...Fail Zero with their Nib setup has run over 50k rounds through their test upper WITHOUT lube...that's a couple barrels at least...

Here's the weight breakdown difference for illustration (adjusted barrel weight for a 16" gov profile, not the 14.5" used on the actual URGI to give an apples to apples comparison):

URGI (Upper Receiver Group Improved, modified with a 16" gov profile vs. 14.5" gov profile for an apples to apples):
Geissel 13.5" SMR M-Lok Handguard 14.9oz
Daniels 16" Gov profile mid-length 556 Barrel 27.2oz
Total: 42.1oz

6.8 URGHB (Upper Receiver Group Heavy Barrel, this is my implementation):
Handguard 6oz
Barrel 36.9oz
Total: 42.9oz

Difference 0.8oz...and more of that weight is at the back of the receiver where the weight matters a lot less than out front. But I have a barrel in a more powerful caliber and in a heavy profile....my 6.8 URGHB would massively outperform their brand new URGI at nearly the same weight and handling.

6.8 URGSCOUT:
JL Billet NANO Ultra Mag / Alu 15" Handguard 6oz
ARP 16" Scout Barrel 28.6oz
Total: 34.6oz

Or if you pin the gas block AND if ARP still has them:

6.8 URGSCOUT14.5:
JL Billet NANO Ultra Mag / Alu 13" Handguard 5.8oz
ARP 16" Scout Barrel 25oz
Total: 30.8oz...that's a pretty lightweight barrel / handguard config for 6.8 SPC.

Even my 5.56 Daniels Light Weight CHF CL barrel clocks in at 24oz...and that's a pencil profile I use for a training upper / CQB upper for an alternate caliber to my 68 that's a primary.

Gas piston system will also add more weight than a DI gas system, even the SA one (lightest piston system of them all) is 3oz more total weight mostly out front than a low profile gas block (1.3oz) and gas tube (0.6oz) in a DI gas system. Carriers are the same weight. So if your weight conscious, go DI. And this coming from someone who ran AA's also reasonably lightweight piston system for years....

View attachment 69693
Note that I have since replaced the bulky picatinny mount surefire pressure pad with sure fire's smaller tape version and magpul m-lock mount plate for a lower profile and cleaner design, no rubber bands or zip ties, but at the time of the photo worked reasonably well still, even if a bit ghetto, I was using what I had at the time of the initial build. That's a heavy barreled 6.8 barrel with JL's mag / alum handguard.

Handles like the oh so typical 16" 556 gov profile / 6601 15" m-lok handguard combo but shoots in a league of it's own comparatively.

P.S. sorry for the uber lengthy post, but there was a lot of technical reasoning to my suggestions. I've tried MANY configurations over the last 10 years and I've really honed in on what works and what doesn't, what's the best and what's marginal. I'm always after overmatch, not just in caliber selection, but rifle design, so I roll my own as they say.
i think I'm gonna go with the light ARP barrel. If I can't get one, I guess any heavy profile barrel

I'm stuck on piston mostly because if I don't use it in this gun, I don't have anything else to put it on, and looking at a box of spare parts that I bought and never used makes me sad. I've already bought the handguard, a CMT 13.7" MOD2. Absolutely tits handguard. I couldn't help but put the whole together with a 5.56 barrel, just to see how it looks. I'll post a pic when I get to my iPad. The weight of this isn't really the end of the world, just would be nice if I could get as light as possible without any real sacrifices. I've already got an ultralight 5.56 (around 4.4lbs and I've still got a couple ounces to go, will post a pic of that too). So that's satisfied my ultralight itch. The problem is mostly finding any SPC2 barrels in stock

Edit: ok after reading a user's post in my SA piston thread, I'm second guessing the piston. Maybe I can use it in my spare parts 5.56 rifle. I have a full mass DI carrier for that anyways. Can just transfer it to the 6.8. Bright side, it saves weight with the gas block and buffer.
 

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Have you considered the route I took? A road far less traveled. You could use my concept but tweak it
Great idea! I was thinking along those same lines myself since I just received the ARP 16" scout barrel for my first 6.8 build. I just bought a 13.5" Jag Composites Carbon Fiber HG for a light weight WWSD (What Would Stoner Do) 5.56 build I'm working on, so I thought, it'd be great to have this 4.1 oz (total w/nut and hardware) HG on the 6.8 build too. It's 1.7 oz lighter than the JL Billet NANO Ultra Mag / Alu 13" HG at 5.8oz for basically the same $$$, and carbon fiber is supposed to be stronger and more heat insulated than aluminum.

I think I just talked myself into buying another one now ?
 

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Looks pretty cool, never saw the JAG before, but it looks like they are for competition applications. My concern would be that the thermals are going to SUCK big time. There's no airflow and carbon fiber is an insulator...while it may not heat up the handguard as much for a short while (just wear gloves), it's going to trap a lot more heat in the barrel which will start to saturate much faster. That robs you of accuracy and barrel life.

Skeletal handguards allow a for a lot more convection cooling and AZ61A has very good thermal conductivity (better than 6061 T6) making it a giant thermal dissipater. You might think intuitively that high thermal conductivity in a handguard is bad, but what it does is dissipate the heat it absorbs more quickly and the skeletal designs convection cooling keeps the barrels cooler longer and allows for faster cool off when they do heat up. The JL Billet isn't a super slim design either, so there's a decent clearance around the barrel (some really get as close as possible for the smallest diameter).

Installation looks pretty standard though: Handguard_Installation.pdf (shopify.com)

But I'm sure it works well for a competition gun, would probably be a good choice for lightweight hunting upper or even a fast deploy truck gun.
 

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I painted mine with rattle can, I don't mind it looking worn etc. as the paint rubs off in contact areas, primary function of the point job is just to visually brake up the outline of the gun which it accomplishes, even when worn. I believe from the factory they are all cerakote in either black or FDE.
 

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Maybe that's the regular 6061 variant I was thinking of. They make them in 6061 T6 as well at a lower cost but I do believe those are painted black by default or maybe it was a heavy type 3 phosphate. Either way, I just remember one I ordered didn't require a color selection, but don't remember which one that was.

I run the magnesium one on my heavy barreled 6.8 upper that's sporting the Razor HD gen 2-E 1-6x + 45 RDS on a badger C1 1.70" mount (lower 1/3), but the 6061 version is on my 556 upper with the Daniels Lightweight profile barrel that just has an RDS, figured why spend the extra $50 when that barrel and optic combo are already pretty lightweight.
 

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Discussion Starter · #33 ·
Great idea! I was thinking along those same lines myself since I just received the ARP 16" scout barrel for my first 6.8 build. I just bought a 13.5" Jag Composites Carbon Fiber HG for a light weight WWSD (What Would Stoner Do) 5.56 build I'm working on, so I thought, it'd be great to have this 4.1 oz (total w/nut and hardware) HG on the 6.8 build too. It's 1.7 oz lighter than the JL Billet NANO Ultra Mag / Alu 13" HG at 5.8oz for basically the same $$$, and carbon fiber is supposed to be stronger and more heat insulated than aluminum.

I think I just talked myself into buying another one now ?
What's the outside diameter on the jag rail? I'm kinda considering one. Right now I have a coda evolution 13.5" rail on my ultralight 5.56. 7.5oz w/ hardware. Want to swap it for the jag but don't want anything too wide, and I know CF handguards tend to be pretty wide.
 

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As a side note, we are approaching the end as we know it, probably the end of the age, I'm not sure a light weight barrel is what you want.
 

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Discussion Starter · #38 ·
I called Wilson. They are not permanently discontinuing the 6.8 barrels but have stopped production on all niche calibers to catch up on the barrel production for popular calibers. They're back ordered 10s of thousands of barrels. Who knows when I'll get it. At this point I'll probabaly ask a friend in another state to take delivery of an ARP barrel for me.

The Jag is an octagon shape that is slightly taller than it is wide. 1.75" tall and 1.5" wide OD.
13.5" came in the mail today.

Seems to be made of 3 layers. Outside carbon fiber, inside some white foam type thing, and inside maybe polymer? Any idea what the other 2 layers are and why it's not 1 piece carbon fiber?
 

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Seems to be made of 3 layers. Outside carbon fiber, inside some white foam type thing, and inside maybe polymer? Any idea what the other 2 layers are and why it's not 1 piece carbon fiber?
I don't know. I didn't notice that. I had a good email conversation with the owner, prior to ordering mine. I just emailed him your question. I'll let you know what he says.
 
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