The legal calibers for deer hunting in Illinois fall into four firearm categories: shotguns of 10 to 20 gauge firing slugs, muzzleloaders of at least .45 caliber, centerfire handguns of .30 caliber or larger, and single-shot centerfire rifles of .30 caliber or larger. Handguns and rifles share the same cartridge rules under 520 ILCS 5/2.25, and several familiar rifle rounds that hunters use in nearby states are not legal here.
Centerfire Rifle and Handgun Cartridges
The core caliber rule is the same for single-shot centerfire rifles and centerfire handguns. The cartridge must be .30 caliber or larger, and it has to fit one of two profiles:
- Bottleneck centerfire cartridges with a case length no greater than 1.4 inches.
- Straight-walled centerfire cartridges, with no maximum case length.
The load must be a factory-produced cartridge, and the manufacturer’s published ballistic tables must show at least 500 foot-pounds of energy at the muzzle.1Illinois General Assembly. 520 ILCS 5/2.25 Full metal jacket bullets are prohibited.
Cartridges That Qualify and Cartridges That Don’t
Straight-walled rounds tend to work well under this framework. The .350 Legend, .450 Bushmaster, and .45-70 Government all clear the .30-caliber minimum and the 500 foot-pound energy floor, and because they are straight-walled there is no case-length cap to worry about.
Common bottleneck rifle cartridges are the trap. The .30-06 Springfield and the .270 Winchester both have case lengths well over 1.4 inches, which makes them illegal in Illinois whether you’re shooting them from a rifle or a handgun.2Illinois Department of Natural Resources. FAQs: Single-shot Rifles and Deer Hunting in Illinois The IDNR publishes a legal cartridge list on its website, though it cautions that the list may not be exhaustive.
Single-shot centerfire rifles have only been legal statewide for deer since January 1, 2023. The rifle must be a true single-shot, holding one round in the chamber with no functional magazine, and it can be used during firearm deer season in any county that allows firearm hunting.2Illinois Department of Natural Resources. FAQs: Single-shot Rifles and Deer Hunting in Illinois
Handgun Configuration
On the handgun side, only centerfire revolvers and centerfire single-shot handguns qualify. Semiautomatic pistols are not on the approved list.3Illinois Department of Natural Resources. Hunting Devices and Ammunition The barrel must measure at least 4 inches. Conservation police officers commonly check barrel length in the field, so a revolver that measures even slightly under 4 inches should stay home.
Shotgun Gauge and Ammunition
Under 17 Ill. Adm. Code 650.30, a deer-hunting shotgun must be no larger than 10 gauge and no smaller than 20 gauge. That covers 10, 12, 16, and 20 gauge; a 28 gauge is too small.4Legal Information Institute. Illinois Administrative Code tit. 17, 650.30 – Statewide Requirements for Hunting Devices
Only slugs are permitted. Buckshot is illegal for deer in Illinois. The shotgun also cannot fire more than three consecutive rounds, so a tubular magazine longer than that needs a one-piece plug that cannot be removed without disassembling the gun.3Illinois Department of Natural Resources. Hunting Devices and Ammunition
Muzzleloader Caliber
Muzzleloading rifles are governed separately under 17 Ill. Adm. Code 660.30. The firearm must be a single- or double-barrel muzzleloader with a bore of at least .45 caliber, firing a single projectile through a barrel of at least 16 inches. The projectile itself must be at least .44 caliber, which means a slightly undersized bullet in a .45 bore, a common sabot setup, is still legal.6Legal Information Institute. Illinois Administrative Code tit. 17, 660.30 – Statewide Muzzleloading Rifle Requirements
Legal ignition systems include percussion caps or primers, wheellocks, matchlocks, flintlocks, and electronic ignition. Only black powder or a black powder substitute such as Pyrodex is permitted, and smokeless powder is legal only in muzzleloaders specifically manufactured for its use.5Illinois General Assembly. Illinois Administrative Code tit. 17, Part 660 – Section 660.30 Statewide Muzzleloading Rifle Requirements
Bullet Type Across Every Firearm
Whatever you shoot, the projectile has to be an expanding one. Soft point and hollow point bullets qualify, as do copper and copper-alloy hunting projectiles designed to expand on impact.3Illinois Department of Natural Resources. Hunting Devices and Ammunition Military-style full metal jacket bullets are prohibited for taking deer with a muzzleloader, handgun, or rifle.1Illinois General Assembly. 520 ILCS 5/2.25
Which Firearms Are Legal in Which Season
Being legal in caliber is not enough on its own; the season has to allow the firearm.
- First Firearm Season (November 20–22, 2026): Shotguns with slugs, muzzleloaders, legal centerfire handguns, and single-shot centerfire rifles are all permitted.
- Second Firearm Season (December 3–6, 2026): Same equipment rules as the first firearm season. Hunters holding a muzzleloader permit may also use a muzzleloading rifle during this season.
- Muzzleloader-Only Season (December 11–13, 2026): Only muzzleloading rifles meeting 17 Ill. Adm. Code 660.30 are legal. No shotguns, handguns, or centerfire rifles.
These dates are set each year by the Illinois Department of Natural Resources.7Illinois Department of Natural Resources. Deer Firearm and Muzzleloader Hunting Information
Penalties for Using the Wrong Caliber
Most equipment violations fall under Section 2.24 of the Wildlife Code and are charged as a Class B misdemeanor, which carries up to 180 days in jail and a fine of up to $1,500.8Illinois General Assembly. Illinois Administrative Code tit. 17, Part 680 Related offenses escalate: hunting outside legal hours is a Class A misdemeanor carrying a $500 minimum fine and up to $5,000; illegally taking two or more deer within 90 days is a Class 4 felony; and taking two or more deer in a single act is a Class 3 felony. A conviction also exposes you to a civil penalty based on species value and can trigger revocation of your hunting licenses and permits.