Not surprisingly, Mr. Herman and other open-carry proponents are opposed to the legislation, a two-bill package. What is surprising are the allies they have found in the fight: gun control activists who oppose the legislation because they do not want any weapons carried on school grounds, openly or concealed, except by the police.

“A concealed gun is no less dangerous than one that is visible,” said Dr. Sonya Lewis of the Michigan-based Physicians for Prevention of Gun Violence at a committee hearing on the legislation.

But perhaps even more surprising than the agreement between open-carry and gun control supporters is the split among firearm owners. Many concealed-carry supporters support the legislation as a compromise that would clarify a conflicting web of laws and court precedents on firearms while ensuring that guns could still be taken into schools.

“This is a very unusual bill in that it’s being attacked by the usual suspects — all the Bloomberg groups — and it’s also being attacked by some of the open-carry groups,” said Steve Dulan, a board member for the Michigan Coalition for Responsible Gun Owners, which supports the bills. “We expect all the folks in the matching T-shirts to be against it. We didn’t necessarily expect some of the guys wearing guns to be against it.”