6.5 CM vs 6 CM within 800 yds. Am I missing something?

[Helislacker]

So I’ve been debating whether to rebarrel my Tikka into a 6.5 CM or 6 CM. I hate reloading and I’ve got tons of loaded ammo, brass, and bullets for the 6.5 CM and a load that shoots very well. With that, I’m wondering if the 6 CM is actually worth it given the trade offs I would have with component cost, time spent reloading, and barrel life. To me the 6.5 generally works fine at the distances I’m willing to shoot animals (generally 750yds max). I ran the numbers and my 6.5 ELD-M (2690 FPS) load dips below 1800FPS at around 800yds at 5K DA. The 6mm running at a roughly equivalent 3000 FPS dips below 1800 at just over 850yds. If it was a 200 yard difference in velocity drop off for the 1800FPS threshold I would be all over the 6mm. However, it seems like it’s not anywhere near that and the bit of extra effective terminal range I’d get with the 6mm would be negligible for my uses and I’d get significantly worse barrel life as well. That matters to me as I hate tinkering with guns and don’t wanting to be swapping barrels every year to 2 years.

With that in mind, am I missing something here with regards to the performance gap between the two? To me the 6.5CM is sort of a middle ground between the .308 and 6mm, when you consider recoil, barrel life etc. Is the increased shootability of the 6mm really worth the squeeze?

Any input is appreciated.

Thanks

 

[hereinaz]

Generally stick with something and don’t change. There isn’t a huge difference, but enough for me.

Besides velocity, what is the difference in wind and drop? That is where differences are made and valuable.

 

[Helislacker]

The 6.5CM is a 6mph gun while the 6CM is roughly 6.5mph. Very negligible difference in making wind calls

 

[freezerfull]

The shoot-ability between the two is negligible. So do you already have another 6.5 creed or is the rifle you want to rebarrel a 6.5 creed currently?

 

[Helislacker]

The shoot-ability between the two is negligible. So do you already have another 6.5 creed or is the rifle you want to rebarrel a 6.5 creed currently?

Rifle I want to rebarrel currently is a 6.5

 

[freezerfull]

Is the barrel smoked? Just wondering why your rebarreling potentially to the same cartridge.

If you have ammo and components for 6.5 cm I’d definitely stick with it

 

[Steve300xcw]

I'd put more thought into how to get closer, than if the 6 is better than a 6.5

 

[Helislacker]

Is the barrel smoked? Just wondering why your rebarreling potentially to the same cartridge.

If you have ammo and components for 6.5 cm I’d definitely stick with it

Yep. Barrel is on last legs.

 

[freezerfull]

Yep. Barrel is on last legs.

10-4. Out of curiosity how many rounds have you sent down this factory 6.5 tube?

I don’t think there are any advantages to going to anything other than another 6.5, the amount of ammo and components just makes this an even easier decision.

If your doing a high volume of shooting with this rifle I’d look for about 5 tikka takeoffs, a vise and action wrench. You’d be set for another 20,000+ rounds.

 

[nm.otter]

Barrel is on last legs.

Given all the stuff you have on hand, and assuming it shot well, I would also explore the possibility of cleaning up the chamber/throat and setting the tenon back a few thousandths to cover that.

 

[Helislacker]

10-4. Out of curiosity how many rounds have you sent down this factory 6.5 tube?

I don’t think there are any advantages to going to anything other than another 6.5, the amount of ammo and components just makes this an even easier decision.

If your doing a high volume of shooting with this rifle I’d look for about 5 tikka takeoffs, a vise and action wrench. You’d be set for another 20,000+ rounds.

Gotta be well over 2k closer to 3k now. I stopped counting about a year ago.

 

[TradLife406]

Less recoil. 6.5 has quite a bit. Especially in a light rifle.

 

[nm.otter]

8# rifles:

 

[Bluumoon]

The 6.5CM is a 6mph gun while the 6CM is roughly 6.5mph. Very negligible difference in making wind calls

I’m more like 8mph wind gun w 6CM and 109s, maybe a little better even.

 

[satchamo]

I’m a 6mm fan so I’m biased but you’re getting a slight nod ballistically and a noticeable reduction in recoil from a 6. Yes, it’s well worth the swap. Hell I’d switch for the sole sake of shooting 108s. That’s how much I like them….

 

[Helislacker]

I’m more like 8mph wind gun w 6CM and 109s, maybe a little better even.

What kind of velocities are you getting/what is your barrel length? Mine is showing pretty 7mph at 3000FPS with a 108gr ELDM. I want to run a 20” barrel so my understanding is I’d be closer to 2900 with average loads.

 

[Bluumoon]

What kind of velocities are you getting/what is your barrel length? Mine is showing pretty 7mph at 3000FPS with a 108gr ELDM. I want to run a 20” barrel so my understanding is I’d be closer to 2900 with average loads.

I live at 6800ft, below is a 9mph 90 degree wind.

 

[Helislacker]

I’m a 6mm fan so I’m biased but you’re getting a slight nod ballistically and a noticeable reduction in recoil from a 6. Yes, it’s well worth the swap. Hell I’d switch for the sole sake of shooting 108s. That’s how much I like them….

For me it would be 103gr ELDx vs 143gr ELDX.

 

[Dave0317]

Do you shoot a .223 as well?

My long term goal is to set up a .223 and a 6cm pretty similarly and do a lot of the practice days with the .223. That has given me the warm/fuzzy about choosing a 6cm and not being as concerned with its short barrel life.

If that’s not an option or not appealing, and the reduced recoil doesn’t sound like enough of a draw, then to me, no the ballistics alone of the 6cm would not sway me away from an already established supply of 6.5 components.

 

[hereinaz]

If you shoot 1000 times in the field/compromised field positions with both 6.5 mm vs 6 mm the difference in recoil will make your groups larger with the 6.5 and you will spot less shots.