6ARC for Small Frame. What’s The Large Frame Equivalent?

[j-dubya]

Since the 6GT in a semi threads seemed to have died off, maybe this will reignite some pros/cons. With the uses and capabilities of the 6ARC in small frames, what would be the equivalent of such in a large frame? Most efficient, all around balance of feeding, barrel life, ballistics, reloading, and even terminal considerations for hunting...same type of ‘balance’ outlined by the 6ARC.

I’ve tried calling and emailing GAP regarding any insight they had on the 6GT, but no response so far. The 6GT looks very appealing to me for efficiency, and the fact that it uses Varget. The drawback to the 6ARC so far is the only powder that seems worthwhile for reloading is not very temp stable. So for times we are in right now with supply and demand issues, and having Varget on hand, I’ve been wondering about building something out of an sr25 right now and hold off on jumping into the 6ARC for a while until reloading data matures a bit. Factory 108eld ammo is climbing above the $2/round mark, and will likely only keep going up.

I know the 6GT is still kind of new, but it seems like one of the top candidates for the potential of an efficient chambering (compared to the creedmoors) with vastly superior ballistics to 308. Any other leadings out there I should look into?

 

[Greedmoor]

If we think along the lines of "what is the heaviest-for-caliber bullet I can get to 2600-2800 FPS" Then I think the new 6.8 Western technically occupies that zone in AR10. The SAAMI drawing says it will do a 175 at 2840. This cartridge probably will not stand a chance against the 6.5 CM for many reasons though, and 6.5 CM with a 130 is a really great choice when considering this efficiency and balance argument.

 

[Coffee_and_Pipes]

I don’t know how well the 6.8 Western would do in a large frame setup. The SAAMI specs say COAL can run from 2.755 to 2.955, and its max pressure is 65,000 instead of .308’s 62,000.

It seems like you could run it in a large frame AR, but you wouldn’t be getting the full benefit of the cartridge. I don’t reload or have any experience with cartridge development / acceptance, but it seems like quite a lot of work to still miss out on what the cartridge should be capable of.

 

[j-dubya]

Due to lack of projectiles that have an appreciable BC for this use, I’m going to have to say anything 6.8 is out.

 

[Yondering]

Since the 6GT in a semi threads seemed to have died off, maybe this will reignite some pros/cons. With the uses and capabilities of the 6ARC in small frames, what would be the equivalent of such in a large frame? Most efficient, all around balance of feeding, barrel life, ballistics, reloading, and even terminal considerations for hunting...same type of ‘balance’ outlined by the 6ARC.

I’ve tried calling and emailing GAP regarding any insight they had on the 6GT, but no response so far. The 6GT looks very appealing to me for efficiency, and the fact that it uses Varget. The drawback to the 6ARC so far is the only powder that seems worthwhile for reloading is not very temp stable. So for times we are in right now with supply and demand issues, and having Varget on hand, I’ve been wondering about building something out of an sr25 right now and hold off on jumping into the 6ARC for a while until reloading data matures a bit. Factory 108eld ammo is climbing above the $2/round mark, and will likely only keep going up.

I know the 6GT is still kind of new, but it seems like one of the top candidates for the potential of an efficient chambering (compared to the creedmoors) with vastly superior ballistics to 308. Any other leadings out there I should look into?

I think the simple answer has been right in front of us for a long time - the 6.5 Creedmoor. But the trend right now is towards smaller and more efficient cartridges and platforms, so IMO anything large frame is the wrong question to start with. But if you have that large frame itch, there's a wealth of knowledge about the Creedmoors in them already, and they present that same balance that the 6mm Grendel variants do in the small frame. Or just step back to the x47L case if you want more magazine room. Seems to me anything shorter is good for efficiency, but moving away from that balance of cartridge vs frame size.

IMO anything on a magnum bolt face in a large frame, or a .473 bolt in a small frame, is out of the running for anything resembling a good "balance". Standard and readily available parts, along with magazines that feed well, are all part of the appeal.

 

[j-dubya]

I think the simple answer has been right in front of us for a long time - the 6.5 Creedmoor. But the trend right now is towards smaller and more efficient cartridges and platforms, so IMO anything large frame is the wrong question to start with. But if you have that large frame itch, there's a wealth of knowledge about the Creedmoors in them already, and they present that same balance that the 6mm Grendel variants do in the small frame. Or just step back to the x47L case if you want more magazine room. Seems to me anything shorter is good for efficiency, but moving away from that balance of cartridge vs frame size.

IMO anything on a magnum bolt face in a large frame, or a .473 bolt in a small frame, is out of the running for anything resembling a good "balance". Standard and readily available parts, along with magazines that feed well, are all part of the appeal.

The x47L’s (or at least their concept) is what I’d had my eyes on for years now, and meant to put that in the OP. But from I’ve gathered from reading about all the loading data and info, they are temperamental with powder. Something about you either have to run higher pressures or run the projectile slower with better pressures. Neither of which are ideal for gas guns. That’s why the 6GT really has my attention, as it’s a shorter capacity case that also prefers to run Varget. Nice and stable. I have never personally loaded either of the x47L’s, so no direct experience with them.

 

[Raufoss]

Large frame? 25x47L or 25 Creed with 131 black jack. Best performance ratio Ballistic/recoil

or you can test your luck with the gay western. Damn you .277 guys are hungry

 

[Yondering]

The x47L’s (or at least their concept) is what I’d had my eyes on for years now, and meant to put that in the OP. But from I’ve gathered from reading about all the loading data and info, they are temperamental with powder. Something about you either have to run higher pressures or run the projectile slower with better pressures. Neither of which are ideal for gas guns. That’s why the 6GT really has my attention, as it’s a shorter capacity case that also prefers to run Varget. Nice and stable. I have never personally loaded either of the x47L’s, so no direct experience with them.

I think in the reloading forum cummunity we sometimes attribute some mystical special properties to certain cartridges, even though we know objectively that it doesn’t work that way. This is a good example IMO. It’s natural that the x47 has lower velocity unless it runs higher pressure, because that’s what happens with smaller case capacity as we all know. The 6GT is not a magic exception to that either, despite some claims, and anything it can do with Varget, you can add 100-200 fps for the right ball powder.

You can use Varget in the 6mm ARC too for that matter. I didn’t like the accuracy at the pressure needed to get the speed I wanted, but it’ll work if a guy is willing to accept the velocity loss in comparison to something like Lever.

Regardless, there’s no perfect case size, just a sliding scale of power and velocity vs powder consumption and magazine length. Pick the speed range you want and figure out the case capacity needed to get there. It’s worth pointing out of course that the relationship between case size and velocity is a curve rather than a straight line, so it requires increasingly larger case capacity for small velocity jumps; that’s why these small cases like the ARC are able to deliver speeds so close to the larger cases.

 

[j-dubya]

Large frame? 25x47L or 25 Creed with 131 black jack. Best performance ratio Ballistic/recoil

or you can test your luck with the gay western. Damn you .277 guys are hungry
View attachment 7533225

Thanks for putting the .25 back on my radar. I had kind I pushed it to the side since I had reservations of being married to strictly one bullet choice, and the expensive endeavor should a gas gun not like that bullet. But seeing that Berger is jumping in the game, I’m going to bring this back to front and center. It really does seem like the best answer for this thread in regards to balance.

 

[j-dubya]

I think in the reloading forum cummunity we sometimes attribute some mystical special properties to certain cartridges, even though we know objectively that it doesn’t work that way. This is a good example IMO. It’s natural that the x47 has lower velocity unless it runs higher pressure, because that’s what happens with smaller case capacity as we all know. The 6GT is not a magic exception to that either, despite some claims, and anything it can do with Varget, you can add 100-200 fps for the right ball powder.

You can use Varget in the 6mm ARC too for that matter. I didn’t like the accuracy at the pressure needed to get the speed I wanted, but it’ll work if a guy is willing to accept the velocity loss in comparison to something like Lever.

Regardless, there’s no perfect case size, just a sliding scale of power and velocity vs powder consumption and magazine length. Pick the speed range you want and figure out the case capacity needed to get there. It’s worth pointing out of course that the relationship between case size and velocity is a curve rather than a straight line, so it requires increasingly larger case capacity for small velocity jumps; that’s why these small cases like the ARC are able to deliver speeds so close to the larger cases.

I was referring to what I had learned about the burn rates for the powders. You either had to run the powder with lots of pressure to get the speeds you wanted, or used faster burning stuff that resulted in less than desirable speeds. Very similar to what the case is for 6ARC right now... I watch that thread very closely to the data you and some of the other guys are developing. THe results of Varget in it kills the deal for me, and Lever’s temp stability is offputting. I know it’s still very young, and I’m watching closely to see how it matures. Factory ammo would be fine for the time being if it wasn’t for our current political climate.

 

[Yondering]

Yep, that's just the way it is for smaller cartridges. Keep in mind you're also mostly seeing results of shorter barreled gas guns vs longer barreled bolt guns for the 6GT and larger, and there can be big differences as a result of that. Also fwiw, powders like Lever and CFE223 work in the same burn rate range as Varget, so anywhere that Varget does well you can bet that Lever will do even better. If you want to just compare Varget vs Varget, then the small cases like 6 ARC give up a lot more to the bigger stuff.

But the way the smaller cartridges are more sensitive to powder type (i.e. needing to use something like Lever to get great speed) is what circles us back around to something like a 6 or 6.5 Creed in an AR10. The larger case is more forgiving of different types of powder, and you can get great results with something stable like RL16 (my personal preference at the moment) while also being the same type of balance in a large frame.

But really it boils down to picking the bullet weight / b.c. and velocity you want to shoot it at, then choose the case size and barrel length that'll get you there. Personally .25 and .277 calibers wouldn't even be on my radar because of bullet choices, but that's why the freedom to choose what we like is so great.

 

[sam4886]

I own a 6mm predator, same as grendel, couple more grains capacity than the arc, in a 22" are. I also own a 24" 6.5 creed bolt gun. The trajectory of my loads using 90s and 143s respectively, is damn near the same out to about 800 yards. The 6mm has a few inches less drop across the board.

So, I'd say the creed in a large frame is going to be your easy button. If you want to get something different, I understand, I usually roll the same way. That's how I ended up with the 6pred a year before the arc was released. I would have just gone with the factory option if it were out when I got mine though.

Oh, and I only shoot "temp stable" powders. The extreme line, mostly.