I started with a CVA .45 Kentucky in 1975. It was fine for small critters, not very much good on deer. I stepped up to a .50 CVA Mountain rifle which my Dad bought from Coast To Coast in 1977. The load for it was 100 grains FFG Goex BP pushing a Poly-Patch and round ball. It took several deer.
I no longer use the .50 cal. rifles. Now I deer hunt only with the .54 Hawken and Mountain rifles. My pet load is 100 grains FFFG Goex BP and either the 348 or 405 grain Powerbelt bullet, depending on terrain. I've not had to track any wounded game since I started with the .54. Impact is much greater than the .50.