Are Automatic Knives Legal in Montana?

The Short Answer

Yes. Automatic knives are completely legal in Montana — to own, carry openly, carry concealed, buy, and sell. No permit required. No blade length limit. Montana is one of the most knife-friendly states in the country, and it earned that reputation by deliberately removing restrictions from its books.

What Montana Law Actually Says

The Statute (§ 45-8-316, MCA — as Amended by H.B. 251, 2017)

Montana's journey to full knife freedom happened in two key steps. The first came in 2017, when House Bill 251 amended the state's concealed weapons statute.

Before 2017, Montana Code Annotated § 45-8-316 was titled "Carrying concealed weapons" and included dirks, daggers, swords, and knives with blades 4 inches or longer in its list of restricted concealed items. H.B. 251 changed the caption to "Carrying concealed firearms" and removed all non-firearm weapons — including every type of knife — from the concealed carry prohibition.

The companion definition in § 45-8-315 was also amended, changing "concealed weapon" to mean a concealed firearm only.

In plain terms: Montana's concealed weapons law no longer applies to knives at all.

What That Means in Plain English

There is no Montana statute that restricts the ownership, possession, open carry, or concealed carry of any knife — including automatic knives, OTF knives, switchblades, gravity knives, Bowie knives, daggers, dirks, stilettos, or any other edged tool. Period.

OTF Knives in Montana

Out-the-front knives are 100% legal in Montana. You can own them, carry them openly, carry them concealed, buy them, sell them, and collect them without restriction. There's no blade length limit for OTF knives or any other type of knife in the state.

Whether it's a double-action OTF you carry clipped to your pocket or a collector piece sitting on your shelf, Montana law doesn't distinguish. A knife is a knife, and Montana doesn't regulate them for law-abiding adults.

Switchblades vs. Automatic Knives: What Montana Considers Them

Montana doesn't draw a legal distinction between switchblades, automatic knives, assisted openers, or any other knife mechanism. The state's criminal code simply doesn't regulate knives by type. There is no statutory definition of "switchblade" or "automatic knife" in current Montana law because there doesn't need to be — none of them are restricted.

This is a significant change from pre-2017 law, where various knife types were lumped in with concealed weapons. The 2017 amendment cleaned all of that out.

Carrying an Automatic Knife in Montana

Open Carry

Fully legal. No restrictions on open carry of any knife, any blade length, any type.

Concealed Carry

Fully legal. Since the 2017 amendment to § 45-8-316, concealed carry restrictions apply only to firearms. You can carry any knife concealed on your person without a permit.

Where You Can't Carry (Restricted Locations)

Montana does have one location-based restriction worth knowing:

Schools. Under § 45-8-361, MCA, it is illegal to possess a knife with a blade of 4 inches or longer, a sword, or a straight razor in school buildings. "School buildings" are defined as all buildings owned or leased by a local school district that are used for instruction or student activities.

A violation is punishable by a fine of up to $500, a jail term of up to 6 months, or both.

Note that this restriction applies to blade length — not knife type. An automatic knife with a 3-inch blade would not violate this statute. A fixed-blade hunting knife with a 5-inch blade would.

Beyond schools, there are no state-level location restrictions on knife carry in Montana. Federal buildings, courthouses, and other federal properties may have their own rules under federal law, but that's not Montana's doing.

Blade Length Restrictions

None. Montana imposes no blade length restrictions on any knife for general carry. The only blade length reference in Montana law is the 4-inch threshold for school buildings under § 45-8-361.

Statewide Preemption

Yes. Montana enacted statewide knife preemption effective April 3, 2019, under § 45-8-352, MCA.

This statute prevents local governments from enacting or enforcing any restriction on the ownership, use, possession, or sale of any knife. Local governments may restrict knife possession on property they own or lease, but they cannot pass broader knife ordinances.

This is important. It means the rules are the same whether you're in Billings, Missoula, Helena, or a town of 200 people. You don't need to check city-by-city ordinances.

What About Assisted Openers?

Assisted-opening knives are legal in Montana. But then again, so is everything else. Since Montana doesn't regulate any knife by type or mechanism, assisted openers are treated the same as manuals, automatics, fixed blades, and everything in between.

Age Restrictions

Montana has no state-level age restriction on the purchase or possession of knives, including automatic knives. There is no statute prohibiting the sale of any knife type to minors. Individual retailers may set their own policies.

Recent Changes

• 2017 (H.B. 251): Removed all knives from Montana's concealed carry statute. Changed § 45-8-316 from "Carrying concealed weapons" to "Carrying concealed firearms." Removed dirks, daggers, swords, and knives with 4"+ blades from the concealed carry prohibition.
• 2019 (§ 45-8-352): Enacted statewide knife preemption, preventing local governments from restricting knife ownership, use, possession, or sale.

Buying Automatic Knives in Montana

No restrictions. You can purchase automatic knives in-person or online and have them shipped to a Montana address. There are no state licensing requirements, no waiting periods, and no registration requirements for knives of any kind.

Montana residents can exercise their own judgment when it comes to knife selection and carry — and that's by design.

Frequently Asked Questions

Can I carry an OTF knife in Montana?

Yes. OTF knives can be carried openly or concealed anywhere in Montana except school buildings (if the blade is 4 inches or longer).

Are switchblades illegal in Montana?

No. Switchblades are completely legal to own, carry, buy, and sell in Montana. They were removed from the concealed carry statute in 2017.

Is there a blade length limit for automatic knives in Montana?

No. There is no blade length limit for any type of knife in Montana for general carry. The only blade length restriction is the 4-inch rule for school buildings.

Legal Disclaimer

This article is for informational purposes only and does not constitute legal advice. Knife laws change — sometimes faster than websites update. Federal, state, and local laws may all apply to your situation, and local ordinances can be more restrictive than state law.

Before purchasing, carrying, or traveling with any automatic knife, OTF knife, or switchblade, verify current laws with official state and local sources. We are not attorneys, and we are not responsible for actions taken based on this information.

When in doubt, consult a licensed attorney in your jurisdiction.