Actually the .303 is sort of tepid in comparison to the US .30 M-2 (.30-06) or the Russian 7.62 X 54R round, both of which were around in WW-I. For that matter the German 8mm will outshoot the .303.
Ballistically, the .303 is about on a par with the old Span Am War .30-40 Krag.
Although it might not reach as far or hit as hard as these other rounds, it is still a round to be reckoned with, and packs a lot more whallop than either the US 5.56mm or the Soviet 7.62X39 round used in the ubiquitous AK-47.
Our government supplied the Afghani “freedom fighters” with a lot of these cheap, surplus Enfields back when they were fighting off the Russians, and now a lot of them have been turned back against us by the Taliban. I have heard that the average Muchmett is pretty casual about maintenance and with the corrosive old cordite ammo the barrels are pretty rotted out, and few of the natives can shoot all that well to begin with - but they are still a very serious threat. Every now and then they get a Mercenary from Serbia or Croatia who is a combat seasoned rifleman and can give our Snipers a real run for their money with even an antiquated Enfield or Mosin Nagant. I rather suspect that the “sniper” (a lot of these shots are made from under 100 meters so I’m not sure the term “sniper” is appropriate) is from away, and probably knows how to vanish into the local population pretty quickly.
“Ballistically, the .303 is about on a par with the old Span Am War .30-40 Krag.”
No, the .303 offers quite a bit more in terms of working pressure and velocity than the Krag.