If you already have that many rifles in that limited range of calibers (.277 - .308) why get another? It isn't going to add anything different or do anything different than those that you already have.

I would add a varmint rifle or something substantially bigger than the 30 claliber rifles that you have. Something like a 35 Whelen, 350 Rem. mag, 444 Marlin, 45-70, 375 JDJ, or even a lever gun in something like a 44 mag or 357 mag.