I I believe it is a cartridge and rifle best suited to collectors of history and not the hunting fields. The cartridge is certainly capable,
Can you explain this, please?
The Lee enfield rifles I have used or handled are old and loose, the chambers are huge and sloppy, the triggers gritty and bumpy with a long take-up, the rifles can't be scoped efficiently, the stock beats a shooter up, they are too heavy, and generally not very accurate. The cartridge is rimmed, not a good fit for any other bolt action design.
I would love to have a good modern single shot in .303, or maybe a double, but the rimmed cartridge is a silly choice to convert a modern bolt action rifle to. So, while I have some nostalgia for both the cartridge and the rifle, I have used them and they hold no more fascination for me.
Anything that a .308 Win can do the .303 did many times long before, so it's not about killing ability. I think the .303 British SMLE is a wonderful piece of our history but does not compare well with more modern designs. That's just me, others can continue using their .303 SMLE's and I'm sure they will kill lots of game and enjoy it.
