Yes, if you accept non-magnum Mauser action you can shave thousands from the price tag. Nothing wrong with standard Mauser action for .375 H&H as Holland & Holland made plenty of such rifles (called magazine rifles not bolt-action rifles). Not sure about .375 Weatherby? Is this H&H improved "half way" between .375 H&H and .378 Weatherby?
375 AI case capacity. Neck up a 340 to 375 and you get a 375 Wby case.
They get more extra velocity over the H&H than the case capacity difference would suggest because 4350 is too slow for the 375 H&H, especially with long spitzers and the 4064 burn rate a bit fast but the 375 Wby will get up to full pressure with 4350. Although with 270 grain bullets Re15 in the H&H narrows the gap a lot.
