One would not want to sell the old 303 British short on effectiveness.
We have many 308 Winchester users on here, and the 303 is basically
a ballistic twin to the 308. Case capacities are virtually identical, and
while the Lee-Enfield may not like higher pressures much, the rounds
are, for all practical purposes, in the same class.
Many years ago, I was working in the valley that is now flooded by the
Mica Creek Dam, north of Revelstoke. The valley was full of moose, so the
Wildlife branch had opened a generous season on moose to thin their ranks
before the valley was flooded. My 303 British accounted for 4 moose that fall,
with only 5 shots fired...this speaks for itself. D.