Much like the .25's I think there are no ineffective cartridges in 6.5 cal.
While I like some more than others there is little doubt that all are effective on medium to big game.
I'd particularly like to have a 6.5x54 Mannlicher Schoenauer or a sporterised T38 Arisaka in 6.5x50R as both of these, like their slightly bigger cousin the Swede, are darkhorses.
The most neglected cartridge in the family and arguably the blacksheep is the 6.5x52 Carcano.
Chambered in a suitable rifle it has all the makings of a good sporter but since the Carcano rifle's reputation can be described as inconsistant at best there's virtually no chance of it making a comeback, especially in these days of hyper velocity of small bore cartridges.
I'm not as tempted as others are by the newer 6.5s like the .260(
which I see as extraneous) or the 6.5/284, but they certainly have their place and a mate has a Browing 1885 6.5WSM wildcat he uses both for competition and hunting and swears by.
Give me a T38, a
good Carcano, a Mannlicher Schoenauer and a M96.
Mind you don't expect anything sensible out of me or even to see much of me for quite a while. :wink:
Put it this way.....you could do MUCH worse than buy a good sporting rifle in 6.5 Swede.