The parameters that determine the choice of bullet for a big bore is similar to those that determine the choice of bullet for a small bore. What do you intend to shoot, and how fast will the bullet be going? The choice of jacketed, mono-metal, or cast bullet is dependent upon the velocity you're loading to. I shoot both cast and jacketed bullets in my .458, and both provide good performance. I wouldn't consider a big game load using a cast bullet in my .375 where the velocity runs upwards of 2300 to 2900 fps depending on the bullet weight; so my cast bullet loads in the .375 (300 @ 1200) are just for small game. Conversely, I no longer shoot any bullets in my .44 other than 325 gr WFNs, as the jacketed bullets do nothing better, except cost more.