PARTS Act of 2025

- First, a silencer/muffler includes any device designed and intended to reduce the sound of a portable firearm and that can be attached to a portable firearm, either directly or via a mount, adapter, or other intermediary that itself is not a silencer.

- Second, a single part qualifies only if it is the “outer tube or other single part” that provides the primary housing or primary structure for the internal sound-reduction components and that attaches to a portable firearm (again, directly or through a non-silencer mount or adapter).

This structure produces several notable changes. It explicitly carves out mounts, adapters, and other intermediary devices from being regulated as silencers merely because they interface between the firearm and the suppressor. It removes the “any combination of parts” language, meaning that most individual internal components (like baffles, wipes, spacers, and end caps), and kits that don’t include the primary housing, would generally no longer be treated as silencers by themselves. The only single component that remains a silencer under the statute is the main housing—the outer tube or comparable primary structure that serves as the core body of the suppressor and attaches to the firearm.

Practically, the bill would keep complete suppressors regulated as NFA items. The key “outer tube” or primary housing would also remain regulated. But the sale, possession, or manufacture of many internal parts could fall outside federal silencers regulation so long as the regulated primary housing is not involved. That would likely reduce ATF’s ability to pursue cases based on constructive possession of parts kits or internal components absent the primary housing, and it would make replacement, repair, and innovation in internal components easier for manufacturers and consumers. It also clarifies that common muzzle devices or quick-detach mounts are not themselves silencers, addressing prior disputes where certain mounts or “solvent trap” components were treated as regulated items.

The bill applies to “portable firearms,” consistent with existing law’s focus on typical small arms. It does not alter the NFA tax, registration, background checks, or transfer rules for complete suppressors or their primary housings. Nor does it preempt state law; states could continue to regulate suppressors or suppressor parts more strictly. The language could have notable effects on modular suppressor designs: under the new definition, only the core housing that attaches to the firearm (directly or via a non-silencer mount) would typically be the regulated silencer. Additional length modules or baffle extensions that do not themselves attach to the firearm would likely be unregulated parts.

Supporters will argue the bill curbs regulatory overreach, reduces legal ambiguity, and protects lawful users—especially sportsmen and shooters seeking hearing protection—by ensuring the law targets the actual suppressor or its primary housing, not every piece of internal hardware. They will note bipartisan sponsorship and present it as a balanced fix that leaves the NFA framework for complete devices intact.

Opponents will argue the change could make it easier for criminals to assemble suppressors by buying unregulated internal parts and 3D-printing or fabricating a tube, making preemptive enforcement harder and potentially increasing risks to public and officer safety. They may also warn that terms like “primary housing” could generate new ambiguity and litigation, especially with novel designs, and that narrowing the definition chips away at the preventive architecture of current law.

In sum, H.R. 631 does not legalize complete suppressors or eliminate NFA controls. It narrows the definition so that, with limited exception for the primary housing, individual or modular internal parts and intermediary mounts are not treated as silencers themselves. The bill’s impact would be felt most in manufacturing, repair, aftermarket parts, and enforcement discretion around kits and components, while leaving the core NFA regime for complete suppressors and primary housings in place.