Minimum calibers huh?
Let's see. Hit a 2300 pound beefalo with a 450 Nitro Express, 480 grains, 2200 fps. Went down. Got right back up. Lucky another barrel was present.
I was actually asking for specific loads, and bullets with both calibers. I have a ton of .375 H&H ammo, but, as it seems to go up like Gold prices, not really sure I want to shoot vermin with gold. Most of it is 300 grain Weatherby softpoints, like 300 rounds, at about a buck a round. To replace it is 3 or 4 times the cost.
30-06 ammo hasn't been cheap, and I do need an excuse to buy a .308, or I was thinking a K31 in 7.5 Swiss.
If I wanted to blow money, I'd convert the CZ 550 to .416 Remington, or more likely, I have a hanker for a .458 Lott.
Another thought is to open the .375 up to .375 Wby. Something about 300 grains @ 2700 fps that pretty much flattens everything out to 300 yards.
Problem is the .375 is pretty much ideal, capacity wise, 5 down, one up, in the CZ 550. With pigs, and other rather large varmits, they tend to be in packs, prides, etc. and magazine capacity can be an issue.