150 yds on deer for a modern muzzleloader isn't all that far.  I agree with the other guy's follow the law,  play with an assortment of powder & bullets ,  chronograph your velocities and place your sky screens a little extra distance from the gun's muzzle as not to pelt either the screens or unit with unburned powder.  Look up the bullets BC and with your velocity then  check bullet drops on one of the online ballistic computer programs.   I know 40 years ago who would believe we would be checking drops on a muzzle loader.  Find the bullet that shoots consistently the best it doesn't matter which bullet it is most any of these are fully capable of handling any deer.  I do cast my own and size accordingly,  I find even with Sabots and cast/swaged bullets  tighter the fit the better for accuracy, but every gun is different.  I do use probably more loose powder than pellets.