Can You Make a Gun With a CNC Machine?

A 5-axis machining center does not know what it is cutting. Give it a model of a lower receiver, a bolt carrier or a trigger housing and it will remove metal to those coordinates. The toolpath does not care about the laws in your country, the intent behind the part, or whether the drawing came from a factory or a garage laptop.

So the answer to can make gun cnc splits into two parts. On the technical side, the geometry is machinable and the tolerances are achievable. On the legal side, the part you are cutting decides whether the job is allowed at all, and that decision happens before any spindle turns.

This page walks through where the legal lines sit, which components are restricted, what a shop can and cannot accept, and the machining problems that make firearm parts harder than they look. Read it before you send a drawing.

In the United States, the frame or receiver is the regulated part. Under the Gun Control Act, a receiver that is already finished and functional must carry a serial number and be transferred through a licensed dealer. A partially finished forging or casting, often called an 80 percent lower, is not treated as a firearm by federal law until the machining is complete enough to house the fire control group.

Once you complete that machining, you have manufactured a firearm. Federal law allows an individual to make one for personal use without a license, provided the person is legally allowed to own a firearm and the gun is not for sale or transfer. Making one for someone else, or making several to sell, moves the activity into manufacturing, which requires a federal firearms license.

There is a second layer. States and cities add their own rules, and some require serial numbers on homemade firearms, ban certain configurations outright, or forbid the sale of the parts kits entirely. A part that is legal in one state can be a felony two states away. The machine shop has no way to verify your local law, which is why most shops decline this work.

Outside the United States, rules vary widely. Many countries treat any firearm component as controlled, some ban private manufacture completely, and export controls can apply to the drawings themselves. If you are unsure which category your part falls into, ask a lawyer who works in firearms law before you ask a machine shop.

• 1
  Frame or receiverSerialized and dealer-transferred in the US once functional; the core regulated part.
• 2
  Barrel and boltOften unrestricted as parts in the US but heavily controlled in other countries.
• 3
  Magazines and stocksRegulated by state capacity and feature bans, not by federal manufacturing law.
• 4
  Silencer and select-fire partsControlled under the NFA; private manufacture is not permitted without registration.

A production machine shop is not a legal test case. GreatLight and most contract manufacturers in this tier decline firearm frames, receivers, silencer components and select-fire parts. It is not a statement about machining ability. It is that the legal exposure sits with the shop that cuts the part, and no tolerance spec justifies that risk.

We do machine legal, clearly documented hardware that happens to look similar on a drawing: trigger guards for airsoft replicas, magazine body prototypes for paintball markers, recoil simulation fixtures for testing labs, and OEM parts for licensed manufacturers who supply their own federal license numbers and purchase orders.

When a licensed manufacturer sends work, we ask for the license before quoting. If you cannot provide it, we cannot take the job, regardless of the geometry. That rule is firm and it applies to every order, including one-off prototypes.

Take the legal issue off the table for a moment and the parts are still difficult. A receiver has deep internal pockets, thin walls and a fire control cavity that must line up with pin holes on a separate axis. Reach is the first problem. A 3-axis mill cannot get a tool into the rear pocket without a long, thin cutter that deflects and chatters.

The pin holes are the second problem. Trigger and hammer pin holes typically sit on a true position tighter than ±0.05 mm, and they must be parallel to each other across the width of the receiver. If they are not, the trigger group binds or the pins walk. This is where simultaneous 5-axis work earns its cost, because the part can be held once and the holes bored from the same datum.

Material adds a third layer. Receivers are often cut from 7075 aluminum or 4140 steel. Aluminum 7075 machines cleanly but moves after heat treatment, so stress relief matters. 4140 in the annealed state is gummy and tears; in the hardened state it needs carbide and light depths of cut. Bolt carrier groups in 8620 or 9310 cases are even less forgiving.

Surface finish inside the action affects function. A rough bolt raceway wears the bolt and collects carbon. We hold Ra 0.8–1.6 μm on functional sliding surfaces and Ra 0.2–0.8 μm where a seal or a tight fit matters. Those numbers are achievable, but they force slower feeds and more tool changes, which is part of why these parts cost more than their size suggests.

Not every firearm-adjacent part needs a 5-axis center. A flat trigger guard, a magazine floor plate or a mounting rail can be cut on a 3-axis mill with two setups and a good fixture. Cycle time is short and the cost is low. Choose 3-axis when the part is prismatic and all features are reachable from two or three directions.

Move to 4-axis when you need features on four sides of a part without re-fixturing, such as a cylindrical receiver extension with cross holes. The rotary table, Ø400 mm in our shop, lets the part index and keep one datum. That removes the stacking error you get from flipping the part by hand.

Simultaneous 5-axis is the right call for receivers, bolt carriers and any part with compound-angle ports or deep pockets. The tool stays normal to the surface, so you can use a stubby cutter instead of a long one and hold tolerance on thin walls. It is also the only practical way to machine an internal cavity with curved walls in one setup.

For low-volume work, rapid prototyping in aluminum or engineering plastic is often enough to prove fit and function before committing to a production run. We regularly cut functional prototypes in 6061 and 7075, then move the same program to a production cell once the design freezes.