I just ordered some of the original barnes 45-70 bullets in 300 grain since Randy has had such good luck with them in his Savage. However I noticed that the .458 300 grain x-bullet has a higher b.c. What would be wrong with shooting those? My .50 Encore shoots 300 grain .45 deadcenter and QT's very well but I want to try the Barnes originals. I am not sure about the properties of the x-bullet and how they would work at blackpowder (777) velocities. Any thoughts?