6cm vs 6arc

[Walkstoomuch]

I have been reading the 223 thread for months and have been convinced I need a lighter recoiling rifle. However I'm struggling to make a decision and would like some input on helping me make an informed decision. I live in Oregon so there is a minimum caliber requirement of .24 for elk so the .223 is out. I'm not very knowledgeable about firearms however own a few and have been shooting consistently for the past 5/6 years. I own a 6.5cm, a 308 and a 7RM and all three are bolt action and have suppressors. I've read that I could turn my 308 (Christensen Mesa) into 6cm or 6arc, is this accurate and what would be involved to make that happen?

My criteria for this rifle are
Something with less recoil than my current rifles, both of these calibers seem to address that. Spotting impacts consistently would be great

I don't hand load and don't plan to anytime soon, so factory ammo is important. The 6arc doesn't seem to have a great deal of options but considering what I've read in other threads and heard on podcasts I plan to switch to a match style bullet of which there seems to be regular availability of.

I will probably putting this rifle in a Rokstok

I shoot 500-700 rounds a year between my three rifles, I assume that means barrel life shouldn't be a big deciding factor so the 6cm is still a good option

This will be a hunting rifle for deer, elk and bear. Seems like both are capable of this with correct shot placement and a good bullet

My self imposed limit in the mountains is 500 yards however I do shoot out to 700 at my local range. Again seems like both are capable of this

A shorter barrel would be preferred as I plan to be putting a suppressor on it, I know length affects velocity which affects bullet performance but not sure how to determine how short I can go with each of these calibers

Is there another caliber that would be better suited to my needs that I should be considering?

 

[Marshfly]

I do know that I just bought Factory ELDM for my new 6ARC and I was able to find it for the same price as 223 ELDM using ammoseek. 6Creed would be significantly more per box.

 

[sharps54]

The other caliber to consider might be 6.5 Grendel.

 

[eric1115]

Something to be aware of is that the ARC is a smaller bolt face, so there's we work involved there. Magazine feeding also is probably going to take work to make it reliable.

6CM is a barrel swap and that's about it. As much as I like the 6mm ARC, the CM is a more straightforward path if you're set on converting your existing rifle.

 

[MuleyFever]

I have heard the 6 and 6.5 have very similar recoil which would make sense as they are using about the same amount of powder, I believe. The 6 ARC would probably give you noticeable recoil reduction over the 6.5. Using the ELD-M though the listed velocity falls just under 2000 fps at 500 yards from a 24" barrel. If you are looking to go shorter with a suppressor your max range may need to come down.

 

[Hurley88]

Something to be aware of is that the ARC is a smaller bolt face, so there's we work involved there. Magazine feeding also is probably going to take work to make it reliable.

6CM is a barrel swap and that's about it. As much as I like the 6mm ARC, the CM is a more straightforward path if you're set on converting your existing rifle.

I thought so too, but just finished a Tikka 6 ARC. Same cost for barrel swap as a 6CM, only extra work was sending the bolt to Kinport Peak to have it reamed for the cartridge base.

Feeds from Tikka S/M/M+ mags no problem. About 50 rounds so far, plus the tons of dummy rounds & brass tested at home to test feeding issues.

So yeah. $100-150 for bolt face is about the only difference.

 

[Mtnmilsurp]

Barnes LRX = 6CM
ELDM = 6 ARC

 

[wind gypsy]

6 Creed would be a straight rebarrel, expect about 25% less recoil than a 6.5 creed.

6 ARC is a different bolt face so you'd have to research if you can have your existing bolt bushed smaller. I'd also research if people have used the standard bdl magazine that CA uses successfully with 6 ARC sized cartridges. If putting in a rokstok you could revise bottom metal set up as well for something more specialized for 6 ARC but that's more $ again.

I think I could be happy with 6 ARC velocities in 22"+ barrel but i would not be happy with 22"+ barrel with a suppressor. Thus my current primary hunting rifle is a 18" 6 Creed.

Putting factory 108 and 140 ELDm ammo in a calculator with assumed powder charges i get the following recoil results in a 9# rifle:
6 ARC: 6.9# recoil
6 Creed: 9.7# recoil
6.5 Creed 12# recoil

The differences are greater if you use a lighter rifle.

 

[passinggas33]

I have both in the same stock, same suppressor, same optics, just different barrels and actions. You’ll be hard pressed to tell the difference between the two but the 6ARC does have less recoil (though not by much). They shoot the same exact factory bullet but the 6CM is going 200FPS faster. So there is that. Like them both. Built the 6ARC for my son and the 6CM for me. Honestly they are so close you are splitting hairs.

 

[khuber84]

Gas gun: arc, bolt gun I'd go 6cm. I know you said factory ammo is a need, there are 22 different loads available on midway right now. Barrel life will be substantially different, but that's not a priority as stated. Hand loads will make the velocity gap even larger between the two cases.

 

[jimh406]

Epic Arms guy on YouTube says 6.5 CM are generally more accurate than other calibers. They don't kick a lot and most manufacturers make at least one model, so I'd be looking that direction.

 

[wind gypsy]

Epic Arms guy on YouTube says 6.5 CM are generally more accurate than other calibers. They don't kick a lot and most manufacturers make at least one model, so I'd be looking that direction.

He’s already got one.

 

[z987k]

6cm is easier. If you don't need the extra velocity just load it down to arc velocities. That gets the recoil the same.

 

[General RE LEE]

700 rounds a year = Could need a rebarrel with 6 CM in 2 years.

700 rounds a year = Could need a rebarrel with 6 ARC in 7 years

6 ARC in a 20-22” barrel Howa Mini will have a 108 ELDM going 1800 FPS at 600 yards. 6 ARC has deer killing power beyond the range that is typical and even ethical depending on the shooter and conditions.

I was going to rebarrel a Tikka CTR 308 to 6 CM, but the 6 ARC fit my needs.

 

[Hurley88]

“A shorter barrel would be preferred as I plan to be putting a suppressor on it, I know length affects velocity which affects bullet performance but not sure how to determine how short I can go with each of these calibers”

This is the main reason to lean towards the 6CM over the ARC. If you want a 16-18” barrel & plan to suppress it then the larger boiler room makes sense. You get the velocity back up there & the suppressor tames the recoil a bit. It’s like moving the fulcrum on a lever. If you hate muzzle devices and plan on a 22” barrel, then the 6ARC is better. In both cases you can have the same bullet at the same muzzle velocity. Just comes down to preference.

 

[Walkstoomuch]

I don’t know how this thread got fired up after 6 weeks of silence but really appreciate the insights. I decided on a 6cm and I’m starting at 18”. Once it gets broke in I may cut it to 16” velocity depending, just because I’ve never had a barrel that short and it appeals to me aesthetically

Ordered a rokstok to put it in but I was one of the later investors so it will be a while before she is fully dressed out

 

[ThorM465]

Not having looked deeply into these specific calibers yet, I'll say this. For me it would come down to this:
6 ARC: If I wanted to run an AR15
6 CM: If I wanted to run a SA bolt gun.

 

[justin davis]

AR- 6 arc
Bolt- 6 creed

 

[Fireflyfishing]

Gas gun: arc, bolt gun I'd go 6cm.

This is my take too.