I've a very close friend, who has always had at least a few .303's in his gun locker and curently probably closer to 150. The .303 Brit #3 was his first big game rifle and it's killing ability on moose made it a favourite of his. The primary ammo, if he could get it, was the 215gr. kling-kore Dominion ammo. I've built him numerous 'better' rifles from .30 cal. to .375 wildcats and currently a .458 2" for his guide backup rifle, but he's just as likely to grab a .303 or Smidt-Rubin 7.5x55 for a quick moose hunt with his kids as any other rifle in the locker.
: At this time, I'm re-barreling a P14 for him with a B.King .308 barrel, and chambering it with a .303 reamer, pilot ground to .300". This is so he can shoot .303 factory out of it if he so wishes, although the prime reason for the tight bore is so he can use 220gr. Hornadys in standard .303 brass, with accuracy. His current .303 FL die set, with an undersize expander ball that doesn't touch, FL sizes .303 brass perfectly for the .308" bullets. The undersize expander ball is merely to hold the primer ejector pin.