Page 98 of the regs.
Muzzleloader Only Season
Any person hunting in a muzzleloader only season, including
controlled hunts, must have in their possession a license with
a muzzleloader permit validation. During a muzzleloaderonly
season, it is illegal to pursue or kill a big game animal
with any firearm, muzzleloading pistol, or weapon other
than a muzzleloading rifle or musket. In addition, the
muzzleloading rifle or musket must be:
• Capable of being loaded only from the muzzle.
• Equipped with only open or peep sights. Scopes and any
electronics are prohibited. Except hunters with a visual
disability may apply for a permit to use nonmagnifying
scopes. (Applications are available at Fish and Game
offices.)
• Loaded only with loose black powder, loose Pyrodex, or
other loose synthetic black powder. Pelletized powders are
prohibited.
• Equipped with a single or double-barrel.
• Loaded with a projectile that is within .010 inch of the
bore diameter. Sabots are prohibited.
• Loaded with a patched round ball or conical non-jacketed
projectile comprised wholly of lead or lead alloy.
• Equipped only with a flint, percussion cap or musket cap.
209 primers are prohibited.
• Equipped with an ignition system in which any portion of
the cap is exposed or visible when the weapon is cocked and
ready to fire.
• For additional information about muzzleloader equipment
visit
https://idfg.idaho.gov/hunt/weapons/muzzleloader.