I converted to 3F in my .50 T-C Hawken after I ran through two pounds of 2F trying to get the best accuracy I could. I ran out of powder at a rondy and could only get 3F. I filled my horn, went to the sight-in range and proceeded to find a load that far surpassed any I got with 2F after only five shots. It made me a believer. It's also the load I shoot to this day, 50 gr. 2F, .490" rb, .015" cotton patch greased with 1K Wonder Lube, Lard, or Crisco.
That's also when I began to understand that rifles tend toward individuality and really should have a load developed for each one.
Three Hawks