I am not shopping for the best caliber, just the best 6.5 caliber of 3 very specific ones ... thanks all!
Match the cartridge to the rifle magazine length of the weapon you like best. The ballistics of all 3 are so close that there really is nothing to choose between.
I would say stick with a 1-8" twist in anything you get however.
The CM was made to use the longest bullets in the shortest magazine and does 98% of what the Swede will do in the standard Mauser length magazines. If you like semi-autos, or rifles (like the Ruger Precision or Mossberg MVP) that use mags made for semi-autos, the CM is definitely the best choice.
The 260 is in-between. The problem with most 260s is the fact that the magazines can be shorter then they need to be for the cartridge in deference to the mass produced factory parts that exist on the production lines. We in the USMC used the 308 length mags from 1965 to this day on our M40s and all it's variants. The Army saw a better way and used the 30-06 length mags on it's M21 so they could seat longer bullets easier and not loose powder capacity. The same dynamic exists for making up a 260. If you get a rifle with any magazine longer then the NATO length 7.62 size, the 260 is as good as any.
The "grand old man" is the Swede. That's what "set the bar". Both the CM and the 260 are trying to match the Swede in cartridge performance. From all practical purposes they both do too.
Loads for the 6.5X55 are down loaded to be safe in the older M94 actions, but the strongest of the 96s and the 98s, as well as all American and Japanese actions are easily able to take top loads with lots of strength left. These same actions can easily handle the thrust and pressure of a 257 Weatherby mag. PPU makes brass as good as any I have used from any maker in the USA or the world, and it's actually cheaper then WW brass. I have read reports that it's "hard to get' yet every single time I have needed any I have made a phone call and it was on it's way the same day. To be sure I was not going to get caught in my own words here, I just checked Graf and Sons to be extra sure and 7 out of 7 are available at the time I write this.
Down side.................. None I can really think of.
If you demand a short action the 260 or the CM will fit your requirements better, but having made rifles for over 40 years now, I have yet to see that the "short action' is really any better at anything anywhere. It's theoretical, and LOTS of people tried the theory for the last 40 years, yet if you look to the 1000 yard competitions the shoots done at over 1000 yards, most of the best shooters are again using long or magnum length actions. and the record scores at the end of each year have not gone backwards.
I made a whole bunch of rifles on short action in the last 40 years and a lot of them on standard and long actions too. You know what I have found is the difference in accuracy?
Nothing!!!!!!!!!!
Appreciate your post - you hit a lot of my unasked questions in short order. The part in bold is the trick - I don't have a bolt action rifle platform I prefer. But the replies have given me a few ideas to sample. Thanks!
