Yes, there is a IDFG Commission rule that allows for a person to apply for a permit to us a non-magnifying scope on your muzzle loader for use during a muzzle loader only big game season. Here is a link to the application and other information.
APPLICATION FOR SPECIAL WEAPON REASONABLE MODIFICATION HUNTING PERMIT
TO USE A NONMAGNIFYING SCOPE WITH A MUZZLELOADER DURING A MUZZLELOADER ONLY HUNT
And here is the rule:
IDAPA 13.01.04.305. REASONABLE MODIFICATION PERMIT FOR SPECIAL WEAPON HUNTING SEASONS.
01. Applications for Reasonable Modification Permits for Special Weapon Hunting Seasons.
a. Applications for reasonable modification permits shall be on a form prescribed by the Department.
b. Individuals using the department form for a reasonable modification permit must complete and sign the application form. Nonresident applicants must have their signature notarized. Each application submitted on the department form shall be accompanied by certification from the applicantâ€™s physician, ophthalmologist, or optometrist stating the criteria limiting the applicantâ€™s ability to participate without special accommodation. The applicant shall certify that the applicant is capable of holding and firing, without assistance from other persons, legal firearms or archery equipment. If the physician, ophthalmologist, or optometrist is not licensed to practice in Idaho, a photo copy of the physician, ophthalmologist, or optometrist medical license must accompany the application. Physicians, ophthalmologists, or optometrists must check the appropriate box for short-term or long-term disability on the application. If the disability is short term and physical mobility is expected to improve, the physician, ophthalmologist, or optometrist must include a date when the disability is expected to end.
c. Individuals must identify the equipment accommodation requested, and explain how the requested accommodation will allow them to participate in the special weapon hunt without enhancing their abilities beyond the limitations and purpose of the special weapon hunt.
02. Reasonable Modification Permits for Special Weapon Hunting Seasons.
a. Reasonable modification permits shall be issued only by the Director of the Department or his representative and shall expire no later than December 31 of the fifth year following the date of issuance.
b. The accommodation must be reasonable and must be consistent insofar as possible with all provisions guiding other participants in the special weapon hunting season. For example, persons with a focusing disability (focal plane) could request the use of optical sighting device without magnification (e.g., sighting devices that magnify the target are expressly prohibited for Archery Only, Traditional Archery Only, and Muzzleloader seasons by Rule 13.01.08, "Rules Governing the Taking of Big Game Animals in the State of Idaho," Section410). The Director or his representative shall determine if the requested accommodation is reasonable, and may deny the application or set a modification different from the modification requested.
c. A copy of the permit shall be carried by the person while hunting in any special weapon hunt