Wisconsin has no magazine capacity limit. State law sets no cap on how many rounds a rifle, shotgun, or handgun magazine can hold, and the phrase “high-capacity magazine” appears nowhere in Wisconsin’s criminal code. You can buy, own, and use a 10-round magazine, a 30-round magazine, or a 100-round drum on the same legal footing. A few situations still deserve attention: hunting seasons, how you carry magazines in a vehicle, federal property, and the moment you cross a state line.
No Cap Under State or Federal Law
Wisconsin is one of the more permissive states on this question. No statute assigns a maximum round count to detachable magazines, drum magazines, or any other feeding device. Purchase is unrestricted through licensed dealers and private sellers, there is no registration requirement, and there is no ceiling on how many magazines you can own.
Federal law does not fill the gap either. The 1994 federal assault weapons ban included a 10-round magazine restriction, but that law expired in 2004 and has not been renewed. As of 2026, magazine size is unregulated for Wisconsin residents at both levels.
Cities and Counties Cannot Add Their Own Limits
Wisconsin Statute 66.0409 prohibits any city, village, town, or county from regulating the sale, ownership, possession, or transportation of firearms or firearm parts more strictly than state law. The statute reaches “ammunition and reloader components,” and magazines fall within “part of a firearm.”1Wisconsin State Legislature. Wisconsin Code 66.0409 – Local Regulation of Weapons
The result is statewide uniformity. A magazine that is legal in a rural township up north is equally legal in downtown Milwaukee. You do not need to check a local ordinance before driving across county lines, and any municipality attempting to enforce its own cap would be open to challenge under 66.0409.
Hunting Is the One Place Capacity Is Capped
Hunting is the exception, and it catches people off guard precisely because general possession is so open. For migratory game birds — ducks, geese, doves — federal and state law both require your shotgun to be plugged or otherwise incapable of holding more than three shells total in the magazine and chamber combined. Conservation wardens enforce this, and a violation can bring a forfeiture and loss of hunting privileges.
Additional restrictions tied to specific seasons and methods of take appear in Wisconsin Administrative Code NR 10.07. Check the equipment rules for your species and season before you head out. None of these hunting-context rules affect what you can own or use outside of hunting.
Magazines in Vehicles
Capacity is not the issue during transport; the state of the firearm is. Wisconsin Statute 167.31 draws a line between handguns and long guns inside a vehicle.
Rifles and shotguns have to be unloaded in the vehicle. “Unloaded” means no shell or cartridge in the chamber or in a magazine attached to the firearm. You can leave an empty magazine attached, or you can detach a loaded magazine and store it separately. The long gun must also be “encased,” meaning enclosed in a case that is fully zipped, snapped, buckled, tied, or otherwise fastened with no part of the firearm exposed.2Wisconsin State Legislature. Wisconsin Code 167.31 – Safe Use and Transportation of Firearms and Bows
Handguns are treated differently. Anyone who can legally possess a handgun may place, possess, or transport it in a vehicle without the handgun being unloaded or encased, and no concealed carry license is required for that.3Wisconsin Department of Justice. Wisconsin Carrying Concealed Weapon Law FAQ A license holder can carry a loaded, concealed handgun on their person in the vehicle. Someone without a license can still have a loaded handgun in the vehicle but should not carry it concealed on the body, which pulls in the separate concealed weapons statute.
The penalty for violating the vehicle transport rules is a forfeiture of not more than $100, plus a weapons surcharge equal to 75 percent of that amount.2Wisconsin State Legislature. Wisconsin Code 167.31 – Safe Use and Transportation of Firearms and Bows
Federal Buildings and National Parks
Federal property inside Wisconsin follows federal law. Firearms are generally banned inside federal buildings regardless of magazine size. Under 18 U.S.C. § 930, possessing a firearm in a federal facility is punishable by up to one year in prison, a fine, or both. Post offices trip up a lot of people: the U.S. Postal Service prohibits carrying or storing firearms on postal property, openly or concealed.4United States Postal Service. Possession of Firearms and Other Dangerous Weapons on Postal Service Property
National parks work differently. You may possess a firearm in a national park unit if that possession complies with the law of the state where the park sits. Because Wisconsin sets no capacity limit, any magazine size is fair game in a Wisconsin national park as long as you can otherwise legally possess the firearm. Federal buildings within those parks — visitor centers, ranger stations — remain off-limits.5U.S. National Park Service. Firearms in National Parks
Driving Into Illinois
This is where Wisconsin owners get into real trouble. Illinois restricts magazines to 10 rounds for long guns and 15 rounds for handguns under the Protect Illinois Communities Act.6Illinois State Police. Protect Illinois Communities Act – Regulation on Assault Weapons Nonresidents get a narrow transit exception: you may pass through with a restricted magazine if the firearm is unloaded and stored outside the passenger compartment (or in a locked container if the vehicle has no separate compartment), and you complete the trip within 24 hours. Stop for anything beyond brief transit, or leave the magazine within reach of the driver, and you are exposed to a criminal charge.
Minnesota, Iowa, and Michigan do not currently cap capacity, but laws change. Check the current law of any state you plan to enter before you cross the border with magazines over 10 rounds.
Employers and Posted Businesses
Private property owners can set their own rules about firearms on their premises, and that includes magazines. There is one carve-out for employees: your employer cannot prohibit you from keeping a firearm or magazine in your own vehicle, even when that vehicle is parked on company property. The employer can require reasonable steps such as keeping it out of plain view or locked up, but a flat ban on firearms in employee-owned vehicles is not allowed. Employers can still ban firearms inside company-owned vehicles and can bar visitors and clients from bringing weapons onto the property.
If you carry into a private business that has posted a no-firearms policy, the exposure is trespassing rather than a weapons offense. The business can ask you to leave, and refusing turns it into a citation. None of this changes the legality of the magazine itself. The restriction is about the firearm being on the property, not the number of rounds it feeds.