While not by some definition a large bore, it's a large bore. There are 450gr projectiles, making it a ounce of bullet. Some define "big" bore by that. Really though it's a bullet with a bit more than twice the weight, travelling at the same speed as a 308win.
Most definitely a reloader bore. My Rigby, at a surprise to me, uses normal/even non magnum powders. Further it is loaded to lower pressures than 416 rem or Ruger. Brass life should be good. All projectile larger bore than .308 are spendy......but I haunt the reloading EE. Most shots, at all game are short range and I would not hesitate to take this rifle to 200yds. My Rigby did something most 416's haven't done, take a Dall ram.