7.62, 7.5 comparisons
Ah, we're beginning to thread the needle here. That's okay if you're a handloader, but at this point, if you just wanna shoot milsurp rifles and milsurp ammo, they're close enough that maybe you should be looking at the guns instead. The Moisin is pretty clunky as an infantry rifle (or carbine!)
but the Swiss K31 is just... smooooooooooth if you're looking for an out-of-the-box shooter with iron sights. The 7.62 x 54R (ick, remember, that means Rimmed!
) has a very slight ballistic advantage over 30-06, but bullet selection for true .308 pretty much outweighs that if you're a handloader. The 7.5 Swiss is very, very close to the .30-06 in performance, no edge there that I can see, and does shoot .308. That takes you to the question of whether you're loading your favorite rifle (Moisin/Mauser/Springfield/Swiss). For my money, that bunch of cartridges is so close that we're talking rifles here, not calibers. Each has its strong points but they're really very much in the same class.
Do you wish to shoot a bunch of milsurp 7.62 x 54R? Cheap, go for it. 7.5 Swiss? Not cheap, but accurate, go for it. 8mm? Cheap, pretty accurate (depends on your rifle) go for it. 30-06? Milsurp ammo sorta cheap, accurate for the most part, go for it.
The point is - if I had a favorite rifle in any of those calibers - and I do, except the Russian - I wouldn't see ballistic advantages so much as I'd see what I like in the rifle. I shoot my 03A3 (Springfield .30-06) more than the others, but man, the Swiss K31 and M98 Mausers both do their jobs VERY well and are not at all outclassed by the 30-06. I do handload, and I suppose if I had to choose hunting cartridges, I'd stick with 30-06 for longer ranges, because my Springfield is scope mounted but the Swiss K31 isn't, and the 8mm bullets for long range simply aren't that many choices, but if I were hunting bear, the 8mm might have a slight edge with the heavier weights.
But... we're splitting hairs here.