There is no replacement for displacement. A 452 bore will throw similarly weighted slugs at lower pressures, more efficiently and with less felt recoil, than a 429 bore. The difference is more pronounced as the bullet weight increases. If one is planning to throw 300's, a 45 is a better option than a 44. If 325's and up are on the menu, a 475 would be a better option than a 45, and so on. Nothing wrong with the 44, it will kill deer with authority, but larger bores definitely have their advantages.