Depends on where your stand is from where you expect (X) to show up. To a lesser extent, it also matters what you mean by BP. If you're shooting a breech loading rifle with optics that's fired with shotgun primers, that's not a BP muzzle loader imho and your 1" at 100 yards would apply.
Conversely, if your talking about a true muzzle loader (PRB) or (boolit) then to make an ethical shot, you ought to be well within 75 yards. The arm is lethal well beyond that so bear in mind a back stop (when you're on the ground and not in the stand) as it is not uncommon for the projectile to pass through large game even after contacting large bone (like shoulder blades). I would zero in the sights at 50 yards for this type of rifle...and would not shoot at anything past 75 yards (fear of bad placement on my end).{I can routinely make hits on man sized "pop-up" (3 sec) moving targets at 300 meters, prone with a bolt action rifle}
What type of rifle (musket?) are you using?
What is the caliber?
What is the projectile type and weight?
What is the powder load you're using?
Where are you hunting?