I'm a 6.5 lover, its a toss up between the .260 and 6.5x284 Norma. Right now I lean to the .260. The 6.5x284 gives you some extra punch, but high pressures and heat has been known to kill 6.5x284 barrels. The .260 is a sweet shooter, very accurate, and with the right loads, extremely good at long range.
I think today that cartridge selection has to be driven by bullets. Second factor, for me at least is recoil.
The 6.5 platforms were driven by both of these with the BC toping out at a little over .610 with some really fine bullets from LAPUA and others such as Cartarucio. The .260 Improved being just about the optimal 3K fps platform, if you don't mind fire forming and two sets of dies, etc.
What intrigues me is the idea of the .404 Jeffrey family of wild cats. The .300/404 and .338/404 are spectacular cartridges, again allow the use of Lost River and other high BC bullets. However, for smaller bullets like the new 180 and 176 grain 7mm bullets with BCs in the .700 range, this cartridge is over bore.
(Get to the point...)
Ok, so if a guy wanted to go to a lighter recoiling package how about shortening the .404 Jeffrey and putting a high BC 7mm in that. Again with three sets of expensive custom dies, until:
The appearance of the 7mm WSM which is the 7mm/.404 Jeffrey short.
Hence, the new optimal long range target round with the 180 VLD at about 2850 fps or better with the F215M! (The 6.5/7mm WSM apparently over bore as well.)
I don't want to hijack this thread, but is there a formula for determining whether a specific wildcat or cartidge is considered overbore or not? Some say the 6.5x284 is overbore others say it is not so (regardless of how far it eats barrels).
I'm looking at the 6.5 and 7mm for my next true long-range platform (1,000 yards and beyond). I'm currently using a 6.5x284 (with two barrels), but am strongly considering a switch to a .260 or other 6.5mm or 7mmproject when these two barrels are gone.
It appears from my personal experience, that funny things happen in a barrel as bullet velocities approach MACH 3 or 3300 fps. We are talking heavy bullets here such as the 142 in 6.5 or the 175 to 190 in the .300 for example.
You apparently pay a price in barrel and component life as you do this. (Not to mention punishing recoil)
This is not really a problem with "hunting" guns as they are fired relatively little in their life as a rule. I mean how many moose or tigers do you shoot in a year as an amateur hunter. :lol:
However, if you want to practice as well as shoot in matches it is better to design a cartridge that shoots a high BC bullet at velocities between 2700 and 3100 fps. No real rule of thumb because in reality all rifles are individuals. That is why (again in my opinion) that the .260 AI is optimal. It projects a 140 grain bullet at about 3000 fps, vs 2600 or so for the .260 Remington. (which isn't bad, of course.)
The 7mm WSM can project a 180 VLD (BC=.698) at about 2700 with really decent accuracy, although I am still working on that one.
When I asked a gunsmith what kind of wear a barrel pushing 6.5/284 saw, he told me that it would need to be set back every 3000 rounds, which is basically about the same wear of a .300 Win Mag. So yeah, the 6.5/284 is pretty heavy on the barrel for it's size.