A local friend of mine has had at least one .303 since he was a little kid.
When I met him at the Jail in June of 1979, that's when he started work there, we pretty much instantly became friends.
To this day, he still has at least 2, .303's in P14's, one of which has a new .308 barrel I had chambered with an altered .303 reamer so it can handle factory ammo if necessary, without problems- and it does. He can shoot any .308 diameter bullet out of it as well, including the 220gr. varieties.
The rifle prefers 150gr. Hornady Interlocks at about 2,800fps.