Banning Unlawful Machinegun Parts Act: New Law Forces Registration of Modified Firearms Within 120 Days

The “Banning Unlawful Machinegun Parts Act,” or BUMP Act, is a new piece of legislation aimed at regulating specific accessories and modifications for semi-automatic firearms. Starting 120 days after the bill becomes law, it will be illegal to import, sell, make, or possess any device or part designed primarily to significantly speed up the firing rate of a semi-automatic firearm or make it function like a machinegun. This prohibition targets modifications that remove the requirement for a separate trigger action for each shot, effectively turning a standard semi-auto into something much faster.

The Clock Starts Ticking: What’s Banned and When

This bill focuses squarely on the rate of fire. A standard semi-automatic firearm, as defined here, fires one round per trigger pull and automatically loads the next. The BUMP Act targets anything that changes that fundamental function. Think of it like this: if you have a legal accessory that somehow lets your semi-automatic weapon fire multiple rounds with a single, continuous action—or even just dramatically increases the speed beyond what’s considered normal—that item or modification is now on the federal radar. The ban on the manufacturing and transfer of these items kicks in 120 days after the law is enacted.

The Cost of Compliance: Mandatory Registration for Current Owners

Here’s the part that will hit existing firearm owners directly: If you lawfully owned one of these modified semi-automatic firearms before the law was signed, you have a strict 120-day window to register it. This isn't a simple form; you must register it under the rules of the National Firearms Act (NFA). The NFA is the federal law that regulates items like fully automatic weapons, short-barreled rifles, and suppressors. This means your previously legal firearm modification now falls into the same highly regulated category as a machinegun. For those 25-45 year-olds who own firearms and may have purchased popular accessories in the past, missing this 120-day deadline could turn a legal possession into a serious federal crime.

Who Gets a Pass?

While the bill tightens the screws on private citizens, it makes sure to carve out exemptions for government entities. The prohibitions do not apply to the U.S. government, its departments, or state and local agencies. If you are a private citizen who registers your modified firearm within the 120-day window, you can continue to possess and transfer that specific registered item lawfully. However, the rest of the market—manufacturers, sellers, and future buyers—will find these items banned or heavily restricted under the NFA framework.

The Fuzzy Line: What Does “Significantly” Mean?

One potential challenge is the bill’s reliance on subjective language. The law bans devices designed to “significantly speed up the firing rate” or make the weapon “act like a machinegun.” For regulators and law enforcement, defining “significantly” will be crucial. Does a small, inexpensive modification that increases the rate of fire by 10% count? Or does it have to be a major change? This medium level of vagueness means that the actual impact of the law will heavily depend on how federal agencies interpret and enforce these terms, creating uncertainty for both manufacturers and consumers who may own accessories that fall into a gray area.