Are Binary Triggers Legal in South Carolina? A Deep Dive…

Are Binary Triggers Legal in South Carolina?

Yes, binary triggers are legal to own, possess, and install in South Carolina. State law defines a machine gun based on a 'single function of the trigger' firing multiple rounds. A binary trigger uses two functions—pull and release—for two rounds, so it does not meet this definition.

Understanding Binary Trigger Function

A binary trigger is a firearm modification that alters the trigger's cycle of operation. In a standard semi-automatic firearm, one round is fired when the trigger is pulled, and the trigger must be released and then pulled again to fire another round. A binary trigger introduces a second firing event into this cycle. With a binary trigger installed, one round is fired upon pulling the trigger, and a second, separate round is fired upon the release of the trigger. This creates a faster potential rate of fire compared to a standard trigger, though it remains fundamentally different from fully automatic fire.

The key distinction lies in the number of actions required from the shooter. Each round fired from a binary-trigger-equipped rifle requires a distinct and voluntary action: the pull or the release. The shooter can choose to fire only on the pull by holding the trigger back and then manually cycling the safety selector to a different mode to safely release the trigger without firing the second shot. This mechanical separation of functions is the central pillar of its legal status at both the federal and state level.

Federal Law and the ATF's Stance

Before examining South Carolina's specific laws, it's important to understand the federal framework. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) is responsible for interpreting and enforcing federal firearm laws, primarily the National Firearms Act (NFA) of 1934 and the Gun Control Act (GCA) of 1968. These acts heavily regulate 'machineguns', which are defined as any weapon that shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.

The ATF has reviewed the design of common binary triggers, such as those made by Franklin Armory and Fostech. In multiple opinion letters, the agency has concluded that because these devices require two separate functions of the trigger (one pull, one release) to fire two rounds, they do not meet the federal definition of a machinegun. Each action results in only one round being fired. Therefore, under current federal law and ATF interpretation, binary triggers are considered firearm parts, not NFA-regulated items. They can be bought and sold without the extensive background checks, tax stamps, and registration required for machine guns.

South Carolina Law: Analyzing the State Statute

With the federal context established, the focus shifts to South Carolina state law. The relevant statute is South Carolina Code of Laws Title 16, Chapter 23, Article 1. Specifically, section § 16-23-210 provides the definitions pertinent to machine guns.

The statute defines a machine gun as follows: "'Machine gun' applies to and includes any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of thetrigger."

This language is critical. It mirrors the federal definition almost perfectly, hinging on the phrase "by a single function of the trigger." Because a binary trigger fires one round on the pull (the first function) and one round on the release (the second function), it does not fire more than one shot per function. Consequently, it does not meet South Carolina's legal definition of a machine gun.

Furthermore, South Carolina has not passed any specific legislation that bans binary triggers by name or that more broadly prohibits 'rate-of-fire-enhancing devices.' The state's firearm laws are generally permissive, and in the absence of a specific prohibition, the legality of binary triggers defaults to their status as a non-machine gun firearm accessory. This legal clarity is important for gun owners in the state. This contrasts with the legal situation in other jurisdictions, such as detailed in our analysis of Utah's binary trigger laws.

Distinguishing Binary Triggers from FRTs and Machine Guns

It's easy to get different trigger modifications confused, but their legal statuses can be wildly different. A true machine gun fires continuously as long as the trigger is held down. This is the 'single function' that both federal and SC law prohibit for unregistered firearms.

A binary trigger, as we've established, requires two functions for two shots. This puts them in a different category than devices scrutinized in states like Minnesota where regulations are stricter. Another device, the Forced Reset Trigger (FRT), operates differently. An FRT uses the energy from the bolt carrier group to forcibly reset the trigger, allowing for extremely rapid follow-up shots with repeated pulls. The ATF has classified some FRT designs as machine guns, arguing that they fire more than one shot with a 'single continuous pull of the trigger.' This creates a legal landscape that can be confusing, much like the rules surrounding forced reset triggers in other states.

For South Carolina residents, the key takeaway is that binary triggers and FRTs are not the same thing mechanically or legally. While binary triggers are currently permissible under state law, FRTs occupy a much more ambiguous and risky legal space due to ATF reclassification at the federal level, which would also affect their status in SC.

Practical Ownership in South Carolina

For gun owners in South Carolina interested in these devices, legality is the first step. Proper installation and use are next. Most binary triggers are designed as drop-in replacements for standard AR-15 trigger groups, but they require careful installation to ensure safe and reliable function. It's crucial to follow the manufacturer's instructions to the letter or have a qualified gunsmith perform the installation.

It's also worth noting that while perfectly legal, the rapid rate of fire from a binary trigger may be unwelcome at certain public shooting ranges that have rules against 'rapid fire.' It's always a good idea to check the range rules before use. You can often find firearms with these components pre-installed or purchase the parts separately by checking current firearm listings.

Owning a firearm with a binary trigger is a significant responsibility. Owners should be well-versed in the mechanics of their firearm and the laws that govern its use. Keeping a copy of the ATF opinion letter for your specific trigger model along with the manufacturer's documentation can be a prudent step. Before making any purchase, it's always wise to review the basics of the firearm acquisition process, as outlined in our guide on how to buy a gun. Understanding these nuances is key, whether you're in South Carolina or researching binary trigger legality in Kentucky.