I agree with both mart’s & MikeMcGuire’s logic.
I think most of the world feels the 375’s are big bores. There was an interesting local ad to sell a 375 H&H, it was noted in the ad this was an “elephant gun”. The Big Bore boys probably consider it a medium - medium bore.

I am Not a real Big Bore boy. But, after shooting the 375’s & 416’s for awhile, I personally consider the 375 a medium - medium and the 416 / 404 as large-medium. I do think they are Big on performance. The 458 is where I consider the Big Bores to begin.
I definitely consider the 8mm’s and 338’s medium bores. And the 8mm as the start of them.
All the above’s only worth is conservation. Hell, some consider a .30 caliber as a big bore. And for their uses probably correctly labeled.



Originally Posted by mart
It's a matter of perspective. To the Criedmore crowd big bore probably starts at 27 caliber. To most of the American shooting fraternity 375 seems to be the cut off. In Britain my understanding is they don't consider it big bore until it is .45 or larger. To Wolfe Publishing it's 8mm or bigger if you go by their Big Bore reloading book.



Originally Posted by MikeMcGuire
From a commercial point of view it is 375 and that is where the market sees things.

Look at the price of a M70 in 375 compared to 338 and down.

With the exception of the 378, 416 and 460 all the Wby calibres are available in the cheapest Synthetic Mark V but the 378, 416 and 460 have the Mark V Deluxe as the entry point.

The M70 338 is the same rifle as the 7mm Remington and 300 Winchester and then M70 jumps to 375 and 458.

Then as was mentioned the 375 is the minimum calibre for dangerous game in Africa.

In expensive custom wood/blue guns is at 375 where things like the quarter rib appear.