85.0 grains is all that short barrel will burn efficiently. But, remember, you are pushing a 279 grain ball out that barrel. That is 63 % of an ounce, and that is a lot of LEAD! You don't have to send it down range any faster.
My Hodgdon Data manual shows 80 grains of FFg behind that PRB will produce 1302 Fps MV. That is all you will ever need to kill a deer, within 100 yards. Since most deer are killed inside 50 yards, you have a good working deer rifle that will do its part if you do yours.
There is NO need to shoot conicals out of it. All that does is add recoil, but not accuracy. The conicals will penetrate completely through a deer, expending their energy on the dirt beyond. A PRB will flatten on impact, make a larger entry and pass-through, primary wound channel, and a much larger exit wound, if the ball exits, rather than hitting a large bone.
You should work on some practice loads in the 60-70 grains area, using FFg powder, to find a light recoiling load so you can really practice shooting that gun before the deer season this Fall. The more correct practice you do, the more accurate in placing the ball where you want it to go you will be when you get a shot at a deer during the season.
With these large bore caliber guns, I am convinced its BOTH the LARGE DIAMETER of a RB, AND, ITS WEIGHT, that makes it such a tremendous killing machine on light skinned game, like deer. If you read the hunting topic on the forum, there are plenty of pictures and true stories of deer and Elk being taken by members using .58 caliber rifles. :thumbsup:
