I do not see any good reason to use a .303. Other common cartridges do as well or better with a wider availability of ammo here in the US.
So I would wonder, "Why a .303?
Ecclesiastes 12:13 -CENSORED-¶Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
14 -CENSORED-For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.