I took the 416 Rigby out prairie dog shooting. 400 grain solids - 2350fps.
Good penetratio. Didn't recover any bullets to check for expansion.
Quick kills though.
Beware, if you do this it's possible to developed a head ache.
My cousin wanted to try it. He refused advice on how to hold the rifle and hold it like he was shooting a 22 rim fire target rifle...