Ditto "UncleNorby".

Did you try any in the 150 gr. to 165 gr. range? The 180 gr. will take up a good deal of cartridge space that could be used for additional powder charge ... i.e. higher muzzle velocity. I have killed a ton of game with a 165 gr. , 30 cal. bullet out of a 308 Win. Not much difference, ballistically speaking, between a 308 Win. and and the 303 Brit.