[MENTION=3512]Zulu[/MENTION]: The 308 is an efficient case, but you can make a calculation if a 308 or a 6.5CM will be more or less expensive. Less powder and cheaper bullets can mean paying back the extra barrel sometimes. Yet you will have to work up loads an extra time. In the end you have to decide if the extra wind bucking abilities of a 6 or 6.5mm is more important than an extra barrel. A 6x47 costs just as much to run as a 308, despite the barrel only lasting half as long.
6x47 Lapua
Berger 6mm 105H $32
Lapua brass $103 (20 reloads) = ($103/100)/20 = $0.0515/rd
Primers $32 = $0.032/rd
Powder $67/kg = ±$0.18/rd
Barrel $650 (4000rds) = $0.16/rd
ammo cost: $0.58/rd
barrel wear: $0.16/rd
TCO: $0.75/rd
308 Win
Berger .30 185H $45
Lapua brass $70 (40 reloads)
Primers $32 = $0.032/rd
Powder $67/kg = ±$0.18/rd
Barrel $650 (8000rds) = $0.08/rd
ammo cost: $0.68/rd
barrel wear: $0.08/rd
TCO: $0.76/rd
If you get less reloads with the 308 brass, it even become more expensive to run. But as above, they cost exactly the same to run as you can see. The extra (double) barrel wear on the 6mm is offset by the compenent costs.
This kind of cost calculating could also show if either of these would be suited if you're just paper punching at 100m/100y most of the time. For that purpose I have a dedicated rifle shooting a 221FB at $0.47/rd. With 2000-2500 rounds per year at $0.19 difference to the 308, this adds up to $400/yr savings. That's 500 rounds of 308W
Whah, it's saturday 2am and I'm getting wasted
Enough with the numbers.