I went this road and neither cartridge gave me any more than the 6.5 x 55 could handloaded.

So I built one of those. Just to be different tho, I built a 6.5 x 57 also with a heavy sporter barrel 28 inches long, on a Winchester Model 70.

The other 2 will give you about a 100 fps most instances with a lot more powder to do so, which equates to earlier throat erosion. Much like the comparison of the 270 and 270 Weatherby, 21% more powder for 100 fps more.

plus you don't have to screw around with brass problems like on the 6.5/284.

A 260 Remington when the bullet is seated out long also competes on the velocity. What I have noticed in 6.5 bullets tho on average, their accuracy at 2800 fps or so, beats their accuracy at 3000 fps or so.

So that is my input. Hope it helps and good luck with it.

Cheers and Good shooting
seafire

I have both calibers. The 6.5-.284 is set up for long range. heavy long barrel bench rest stock. 6.5-06 is a sporter weight gun for deer and antelope.Have heard the 6.5-.284 has a short barrel life.I would chose the one that is more available in Austraila.