To some anything above a 22 LR is big-bore, to some anything smaller than 50 cal is small arms. To others anything smaller than a 8 bore is not a "Big-Bore". To some a 45 ACP camp gun is a big-bore while a 416 Weatherby is a medium-bore.
It's so confusing...
Not at all. The vast majority of shooters see Big Bores starting at the 375. They do not see the 45 ACP, 44 Magnum etc. as Big Bores. This reflected by guns/ammo/hunting sites as Karl's post has shown. Manufactures like Winchester, Weatherby, Kimber to name three see the 375 lumped together with the 458 Winchester and 458 Lott and Wby put the 378 together with the 416 and 460 Wby.
