The realization that I am getting old came about after reading this post. I can't believe I have been shooting MLs for over 40 years! Even before PA came out with its primitive season. This required us to use only open 'buckhorn' type sights and round ball and flintlock ignition. Calibers must be greater than .44. Everythng is the still the same except now you can use any projectile shich makes conicals and saboted bullets legal. Shooting deer with the flinter and a PRB wasn't really a problem. We got our share. But most of the time it was due to, like a couple other members said, some exhaustive tracking. Even on dead nuts, behind the shoulder, double lung hits. Why, because the PRB did not expand nor exit and left a scant, if any at all, blood trail.
The rifles we used back in those days were either T/Cs with a 1:48 twist or Lymans with a 1:66 (I think). The switch to conicals was an improvement over the PRBs because now most of the time we got pass thrus which gave us a bit mor blood to follow. And occasionally we got the great DRT result.
But then along came Green Mountain Barrel Company with is 1:28 Long Range Hunter for the T/C Hawken, Renegade and Lyman muzzies. When matched up with a quality saboted bullet and the right powder/charge you now had a sidelock ML that could pretty much keep up with the inlines. And depending on how well your eyesight was, you had a legitimate 100+ yd muzzleloader while still maintaining the traditional graceful lines of the sidelock. And now, as I am getting even older, and hope to continue to do so, in the rifles that are capable of shooting a saboted bullet accurately, I will continue to use them simply to make my job of tracking easier and to give the animal the quicker kill it ethically deserves.
Now, with all that being said - I will have no qualms loading up my .54 with a big ol PRB and having it slam into the side of a poor little whitetail. If I hit shoulder, I am pretty sure it will get his attention and possibly knock him down. But if my aim is true and I sneak it behind the shoulder(s), I am pretty sure it will have enough energy to punch on thru and the trial will be short.