I have performed a whole lot of penetration testing, and loaded correctly, the .454 doesn't offer any advantages over the .480 from a penetration standpoint. In fact, if you push a hardcast too fast, the nose degrades and they don't penetrate very well.

I have a .50 Alaskan revolver that pushes a 525 grain bullet at nearly 1,600 fps (verified) from my revolver. At a Linebaugh Seminar a few yers ago, that load out of my revolver penetrated 50 inches. The exact same 525 grain bullet out of my buddy's .500 Linebaugh at a whopping 1,100 fps went the exact depth as the .50 Alaskan -- 50 inches. The additional velocity (nearly 500 fps) offered absolutely no advantage in penetration. Now, if we were using Punch bullets, the outcome would be different.

The .480 is a .475 Linebaugh that is a little vertically challenged. While it can't push the heavies quite as fast as the .475, it's in the same ballpark when it comes to terminal performance.