Most all of the following has been covered by others but since there are so many haters and jokesters about the CM, I thought I would throw out a few 'pitches' for the CM. While the CM isn't the best of anything (except maybe the best marketing) it gets above average marks in almost all metrics. Some examples are:
1. Cartridge efficiency. My imperfect equation for cartridge efficiency is to divide the ft lbs of energy by the qty of powder it takes to generate that amount of energy. This will give you a ft lbs of energy per grain of powder number. Do the math for muzzle and for an arbitrary mid and long range distance for comparative purposes against other cartridges. You can do the same sort of math for bullet drop and wind drift with the 'typical 130-140 class' bullets as well. You will find that the efficiency numbers are better than many tried and true cartridges. If you take away the 'overkill' (the energy on target at close range that is well in excess of what is needed to effectively kill an animal) that other cartridges create, the creedmoor looks even more attractive.
2. Optimized twist rate- I can't tell you how many cool rifles/cartridges I have owned or come across that I have said to myself......'man I wish this rifle had a faster twist (examples 1:10 twist 243 win, 1:12 twist 308, 1:9.5 twist 7mm RM)' I have yet to come across a factory offering in 6.5 CM that isn't an 8-twist. So, ammo selection/availability relative to available twist rate is a non-issue.
3. Medium to long range target capability. My shooting friends and I routinely shoot long range targets. While we varied rates of success on targets 1200-1500 yards based on skill level and wind-reading ability, it isnt the cartridge that limits our ranges. Example of the opposite example is the 308. For most of us, our realistic ranges for 24", 1:10 twist 308s with 168-175 grain pills get's pretty squirrely around 1100 yards. That may or may not be a limiting factor for some, but comparably, the CM does get you out there more.
4. Recoil- When it comes to recoil analysis, there are lots of folks that comment that they are not recoil sensitive, and that recoil doesn't bother them. Fact is, there are many good shooters that can shoot 7lb magnums very accurately. No argument there. However, if you enjoy target shooting, and don't always have a buddy on a spotting scope, spotting hits/misses is a factor. There are ways to mitigate recoil, and make it almost a non-factor, but from a comparative perspective, the recoil is on the lower end of the spectrum for cartridges with similar capabilities.
5. Ammo availability. During 'normal' periods of time the ammo is abundant, reasonably priced and easy to find, with lots of selection. When we are in 'crazy' times like now, you can still find it without an extraordinary amount of effort, and with decent selection.
6. Market acceptance- Like it or not, all of the manufacturers have accepted the 6.5 CM, which tells me that the availability of ammo, aftermarket, components, new rifles, etc isn't going anywhere.
7. Inherent accuracy. I almost hate to use this term, but if such a thing exists, the 6.5 CM cartridge has it. I have either bought, built, rebuilt, dozens of 6.5 CM rifles. I have yet to have or know of a CM that doesn't shoot, no matter the price point. I am sure there are stories to the contrary, I just don't have any. My most recent experience was a T/C Compass II. After deals, discounts and rebates $205.00. I did a 25 shot load development in a hurry to use the rifle on a last minute hunt. End result was a 3/8 MOA load verified out to 300 yds. Crazy! Maybe crazy lucky, maybe not just luck. It happens often enough among my friends that I would definitely take a chance on a bargain rifle like this in this cartridge before I would do the same in 308 or 243. Another factor for me is the ability to seat bullets very close to the lands and still fit in a normal AICS type magazine. I have tried seating high- BC bullets near the lands with 308 Win and 7mm-08, and both end up with crazy amounts of jump in order to fit in the magazine.
8. Successful variants- While it isn't a real measurable, I do believe that there is something to say about cartridges that ended up with lots of very successful variants. Like the 308 (243, 7mm-08, 338 Fed, 260 Rem, 358 Win), and the 6mm BR (can't even list them all) the 6.5 CM has given birth to the 6mmCM, the 22 CM, the 25 CM. I think it lends credit to the parent case.
9. Resale- This may mean nothing to many, especially those of us that don't typically sell many firearms. But, if you did have a 6.5 CM, it would be one of the (currently) most desirable and easiest to sell on the secondary market. This goes for complete rifles and individual components.
By now you might say 'this guy is a fan boy for the 6.5 CM'. Fact is I am a fan, but not so much that I only own this cartridge. And for what it is worth, I am not new to rifle ownership (not even close). I just like what the cartridge has done for the sport, and it deserves some recognition for that. It is more than just marketing hype.
Happy Thanksgiving!