If you use a load of about 80 grains of Goex FFg powder under that PRB, you should be able to shoot right through both sides of a deer, leaving a massive primary wound channel, out to 100 yds. That is a very long shot on deer, for most places where you find them. Wind drift becomes a problem for taking shots longer than that, as well as trajectory, which drops off rather quickly after 125 yds or so. Better to pass on such shots, than to try to guess, and risk only wounding or crippling a deer. If the deer is worth shooting, its worth respecting it enough not to cripple it. At 11.5 grains per cubic inch, your barrel will only efficiently burn a maximum of 85.8 grains of powder under a PRB, so there is no need to consider using more powder. You can load more, but it will either provide a nice burning flash outside the muzzle, or fall to the grouns unburned. It will contribute more recoil to the load, and if your hawken has the standard hooked buttplate, your upper arm will surely feel That. at 80 grains, that ball should be traveling out the muzzle at over 1600 fps, which is a pretty good speed. Some books list the velocity much higher than that.
