I don't have a super duper rifle chambered for the 6.5CM, simply because I have a 6.5x55 Tikka T3 and a 6.5x57 Mannlicher Schoenaur, that shoot extremely well and fill all of the requirements I have for the 6.5 caliber.
That being said, I do have Turkish ATA rifle, which leaves a bit to be desired out of the box, chambered for the 6.5CM.
Let me explain this rifle's issues and I will get to the load development.
The ATA's bedding is not what anyone would call conducive to accuracy. It takes some fancy bedding at the front of the receiver and the rear of the receiver has almost no bearing surface to bed the rear of the receiver to.
After the perfunctory take down and cleaning, etc from out of the box, it was obvious the rifle was built well and the Walnut stock was beautiful. However, because of the rifle's design, likely to get around international patents on different firearms, the rifle needs some tweeking to be consistent.
Once I was satisfied with the rifle's ability to settle solidly into its bedding, I broke out a bunch of components to play with.
I used three different powders, all of which do their best with magnum primers.
WC852 which is nothing more than a surplus lot of the very consistent H450 (commercially discontinued) and would be classified as a ''ball'' powder.
This powder was very consistent in just about everything I've used it for.
Very similar to VV550 in burn rate.
Bullets were Hornady 129grn #2620
Accuracy was very good, after a couple of fouling shots.
The next powder I used was slower, H414SL10 (W760), 41.5 grains.
Hornady 129 IL #2620
CCI 250 primers.
2800fps
Sub MOA groups out to 200yds.
The third powder I tried was Superformance, 42.0 grains
same bullets and primers
Sub MOA groups out to 200yds
Average 2865fps.
I also tried some VV550 but didn't pursue it.
Accuracy was OK, around 1,5 MOA and velocities averaged 2750 fps, with as much as I could get into the case. Primers were flattening with this load, so because the other powders worked so well with the Hornady IL bullets and Lapua cases. I didn't bother with more development.
From my very limited experience with the 6.5CM, it's a very good little cartridge, if it's chambered in a decent rifle and the shooter does their homework.
OP, my info is for a guideline only. The loads may be to hot for your rifle. Do your own due diligence and don't rely on info that hasn't been verified.
There is a ton of information, from various component manufacturers on SAFE and accurate loads for this cartridge.
Do your own DUE DILIGENCE. It's fun and very interesting, especially if you keep notes, clean when accuracy starts to wander or when you play with OALs and screw torque values.
Just remember, each rifle and set of loading dies are entities unto themselves. Very few of them are created absolutely equal.
Then, get to know your personal needs and capabilities.
