For years, deer hunters across parts of the Midwest had to study cartridge case dimensions before heading into the woods. Straight-wall cartridges like the .350 Legend and .450 Bushmaster grew popular in no small part because they gave rifle hunters legal alternatives in states that heavily restricted traditional bottleneck cartridges.
That landscape keeps changing.
Michigan, Indiana, and Iowa now give hunters considerably more flexibility than their old regulations allowed — though the rules, and when they changed, differ in each state.
Michigan Drops the Limited Firearms Deer Zone
Michigan made the biggest change for the 2026 season.
The Michigan Natural Resources Commission eliminated the Limited Firearms Deer Zone in the Lower Peninsula. Beginning September 12, 2026, hunters can use all legal firearms across the Lower Peninsula — including bottleneck-chambered rifles.
Michigan defines a legal rifle during applicable firearm deer seasons as one firing any caliber larger than .22 rimfire.
For hunters who spent years selecting cartridges specifically for the zone, that’s significant. Straight-wall cartridges are still legal; they’re just no longer required simply because you’re hunting the southern Lower Peninsula.
One capacity restriction is worth remembering for AR-platform and other semi-auto hunters: a semi-automatic rifle or shotgun can’t hold more than six shells in the barrel and magazine combined.
(Michigan DNR 2026 deer regulations: https://www.michigan.gov/dnr/managing-resources/laws/regulations/deer)
Indiana Standardizes Rifle Rules
Indiana took a different approach.
The state now permits centerfire rifles firing a bullet at least .219 inch, or 5.56mm, in diameter on both public and private land.
That public-versus-private distinction matters because Indiana previously maintained different rifle-cartridge restrictions depending on where you hunted. Senate Enrolled Act 280, passed in 2025, eliminated that distinction.
The state still prohibits full-metal-jacket bullets for deer and limits hunters to carrying no more than 10 cartridges for each such rifle while hunting deer.
In practical terms, Indiana hunters now follow a much simpler standard: centerfire, .219-inch bullet diameter or larger, with an appropriate hunting projectile. Meet the diameter and it’s a legal rifle — which puts a common AR-15 in 5.56 or .223 on the table, loaded with expanding bullets.
Iowa Is Still Different
Then there’s Iowa.
Iowa allows both straight-wall and necked-down cartridges during its youth/disabled and first and second shotgun seasons — but that doesn’t mean you can grab your .308 or 6.5 Creedmoor and head for the stand.
The cartridge must fire an expanding bullet measuring from .350 through .500 inch and generate at least 500 foot-pounds of muzzle energy.
That makes cartridges such as the .35 Whelen, .350 Legend, .358 Winchester, .450 Bushmaster and .45-70 Government legal options.
It excludes common smaller-diameter bottleneck cartridges — the .308 Winchester, .30-06 Springfield, .270 Winchester and 6.5 Creedmoor — from those seasons. Note the reason: Iowa cares about bullet diameter and energy, not case shape. A bottleneck round that clears .350 (the .35 Whelen, for instance) is fine; a .308 isn’t, because it’s too small.
There’s another important distinction: this isn’t a new Iowa rule for 2026.
The framework allowing these rifles dates to legislation passed in 2020 and administrative rules effective in June 2021. Hunters may be hearing more about expanded Midwestern rifle options this year because of Michigan’s change, but Iowa has operated under its current rules for several seasons.
(Iowa DNR deer hunting page: https://www.iowadnr.gov/things-do/hunting-trapping/types-hunting-trapping/deer-hunting)
Straight-Wall Isn’t Dead
None of this means the Midwest’s straight-wall boom is over.
The .350 Legend, .450 Bushmaster, .45-70 and their kin still make plenty of sense for whitetail, particularly in timber and where shots are short. Plenty of hunters already own rifles chambered for them, know their holds, and shoot ammunition that performs.
The difference is that regulations increasingly give hunters more choice. Michigan effectively removed case geometry from the equation in the Lower Peninsula. Indiana uses a minimum bullet diameter requirement rather than restricting hunters to straight-walled cartridges. Iowa allows necked-down cartridges, but only inside a fairly specific caliber, projectile and energy envelope.
Three Midwestern states, three different sets of rules.
As always, check current state regulations before heading into the field. The fact that your deer rifle is legal on one side of a state line doesn’t mean it’s legal on the other.