Home Forums Hunting & Shooting Long Range Hunting Which 6.5 and why?

I'm thinking of building me a 6.5 - something or other. I'm tossing out the question here to get some feedback/ suggestions / education / information to help me decide which one.

My goals are:

-Consistent 500 and in shooter.
-Occasional target and hunting out further - hunting to around 700 and target out to 1000 (further if I can find a place to shoot that far)
-cases fairly easy to find off the shelf or to make from off the shelf brass
-Can handle a wide variety of bullet styles
-Built on a 700 or Mauser long action (because I have those already)
-muzzle velocity of 3000 or slightly more with a 140 gr
- sporter-weight barrel

What I'd like to find out is:

- what cartridge and why?
- barrel length
- anything else I should be thinking of in regards to the 6.5 cartridges.

Thanks in advance.