You have never seen or heard of any .303 British ball Mk7 and Mk8 both in 175gn....? They were using that kind of stuff way back 1940s.
what about .303cal 190 grain ball, never heard of that either?
Mk VII was a 174 gn bullet and Mk 8 while nominally a 175 gn bullet (though heavier bullets were sometimes loaded) was for beltfed machinegun use. While it could be de-linked such use was for emergencies only, as the Mk 8 load was known to be very erosive of rifle bores. It would be unlikely that anyone would pull apart some Vickers gun ammo to shoot in their double, and nor would it regulate if the rifle was regulated for standard 215 gn (as those I've seen have been) or Mk VII ammo.
As well, the Mk 8 ball load is not what you actually described:
Some have used their favorite .303cal SxS chronographing 175gnRN 2000mv and drilled their eland dead at 195yd.
A 175 gn RN at 2000 fps doesn't match any .303 load of which I'm aware, and I've owned and used .303s for the better part of 40 years. Nominal velocity for a 174 Mk VII in a SMLE is 2440 fps, 400-odd fps higher. Who built a double to regulate for such a downloaded round?
