Semiautomatic firearms are popular choices for self-defense in the U.S, due to their reliability, ease of use, and wide range of calibers and long gun and handgun options. Self-defense situations demand speed and reliability, qualities that semi-automatic firearms deliver, especially with the use of detachable magazines.

Despite their practicality, however, legislation like Colorado’s Senate Bill SB25-003 highlights ongoing efforts to limit their availability, emphasizing the importance of understanding both the benefits and responsibilities of owning these firearms.

Gun owners should also consider the critical role of self-defense legal protection for protecting their rights and freedom. Organizations like Second Call Defense offer essential protection, ensuring legal and financial support in the aftermath of a self-defense incident, especially as legislative challenges continue to evolve.

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What Are Semiautomatic Firearms?

Semiautomatic firearms are nothing new, they have been around for over 100 years. The first successful semiautomatic rifle is attributed to Austria-born gunsmith Ferdinand Ritter von Mannlicher, who introduced the Model 85 in 1885. The first successful semiautomatic pistol was the Hugo Borchardt C-93, unveiled in 1893. Famously, American designer John Browning is credited for developing the locked-breech action used in many modern semiautomatic pistols, including the iconic Colt M1911 introduced in 1911. Pistols in the 1911 design using detachable magazines are still in common use today for self-defense, sport, and law enforcement.

A semiautomatic firearm is designed to fire one round per trigger pull, automatically chambering the next round after firing. This eliminates the need for manual action to load the next round such as racking a bolt or lever, after each shot. Many models of rifles, shotguns and handguns are semiautomatic functioning. Compared to manual-action firearms like revolvers, pump-action shotguns, or bolt-action rifles, semiautomatics offer significant advantages in speed and efficiency, particularly in high-stress situations.

It is important to understand the distinction between semiautomatic and fully automatic firearms. Fully automatic firearms (i.e., machine guns) continue firing as long as the trigger is depressed. Semiautomatics, on the other hand, require a trigger pull for each shot. Generally, fully automatic firearms manufactured after 1986 are mostly limited to the military, law enforcement and specific FFL dealers. Notably, machine guns are not illegal at the federal level. Automatic firearms manufactured before 1986, commonly referred to as “pre-ban” automatic firearm, can be purchased and sold by civilians so long as they are not a “prohibited person” or live in one of the states that doesn’t allow them. Because they are in limited supply, however, they are generally prohibitively expensive to purchase and maintain.

 

Semiautomatic Operating Mechanisms

Semiautomatic firearms use various mechanisms to cycle their actions, with four primary systems being the most common: short-recoil operation, blowback operation, gas operation, and delayed blowback. However, there are a few other, less common recoil systems.

Short Recoil. Short-recoil operation is widely used in semiautomatic pistols and some shotguns. With this system, the barrel and slide move rearward together for a brief moment after firing, allowing the chamber pressure to drop safely before the barrel unlocks from the slide. The barrel then tilts or rotates to disengage from the slide, which continues traveling rearward to eject the spent cartridge, strip a new cartridge from the top of the machine, and then move forward to chamber a new round. This mechanism is favored for its reliability, efficiency, and ability to handle high-pressure cartridge loads. Many common handguns use this system, like the Glock 19, SIG P320, and 1911 variants. Learn more here.

Blowback Operation. Blowback operation is a simpler mechanism commonly found in smaller pistols, submachine guns, Pistol Caliber Carbines (PCCs), and rimfire rifles. Here, the action cycles purely by the force of the fired cartridge, which pushes the bolt or slide backwards to then strip a fresh cartridge and then forward to chamber it. While easy to manufacture and maintain, blowback systems are typically limited to low-pressure calibers like .22 LR, .380 ACP, and .32 ACP. Learn more here.

Delayed Blowback. For higher-pressure calibers, delayed blowback mechanisms, such as roller-delayed (used in the HK MP5 and JP-5), gas-delayed (HK P7), or lever-delayed (FAMAS), introduce mechanical delays to slow bolt movement and safely manage chamber pressure. Delayed blowback actions typically generate less recoil than blowback and short recoil variants. Learn more here.

Gas Operated. Gas-operated systems dominate modern semiautomatic rifle platforms, such as the AR-15 and AK-47. These systems channel gas from the fired cartridge to a piston (less common) or directly to the bolt carrier, driving the action. Learn more here.

Each of these mechanisms have various trade-offs between simplicity, reliability, accuracy, and suitability for different calibers and pressures, ensuring they meet the diverse needs of firearm users. As already mentioned, there are more than a dozen other variations of mechanisms of action of semi-auto firearms, the above are the most common.

 

The Role of Detachable Magazines

Semiautomatic firearms use a variety of ammunition feeding systems, including detachable box magazines, tubular magazines, and internal fixed magazines. Detachable magazines are frequently used in semiautomatic handguns and rifles and are increasingly common with shotguns. Detachable magazines are designed to be easily removed (detachable) and replaced, allowing users to quickly reload without having to change their position or posture.

Using detachable magazines in semiautomatic firearms greatly enhances their effectiveness for self-defense. They enable faster reloading, which is critical when facing multiple threats in a home invasion scenario. Additionally, detachable magazines are generally more reliable than alternatives like tubular magazines, as they reduce the risk of feeding issues and are less prone to malfunctions. Detachable magazines also enable users to carry multiple pre-loaded magazines, which can be quickly swapped out to address prolonged or unexpected defensive scenarios. Importantly, detachable magazines are considered safer than tubular or internal fixed magazines, because they enable safe unloading practices.

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Unfortunately, 14 states and the District of Columbia have enacted laws restricting magazine capacity. These laws weaken the effectiveness of semi-automatic firearms for self-defense. Limits on magazine size force law-abiding citizens to reload more often, putting them at a disadvantage against attackers who ignore such laws. Many lawsuits have been filed to overturn these laws but ultimately, the Supreme Court of the United States will have to weigh in.

 

Advantages of Semiautomatic Firearms for Self-Defense

1. Semiautomatic firearms enable rapid follow-up shots without manual reloading, an advantage when facing multiple attackers or if the initial shot doesn’t neutralize the threat. It enables the user to fire quickly under stress without having to manipulate a manual action, which is invaluable in emergencies, especially if you are injured and do not have the use of both hands.
2. Semiautos equipped with detachable magazines often hold more rounds than other firearms, making them ideal for situations requiring sustained defense, like home invasions. This is especially true of full size, 9mm pistols and AR-style rifles. Quick reloads further enhance their effectiveness.
3. Available in a variety of calibers, sizes, and configurations, semiautomatic firearms can be tailored to individual needs, from concealed carry pistols to home defense rifles and shotguns. Accessories like optics, lights, slings, etc. further enhance their utility.
4. Semiautomatic firearms often have better ergonomic grips, are lighter weight and with quality triggers, very consistent trigger pulls and resets making them ideal for both experts and novices.
5. Because semiautos require less manual action to operate (you still must manipulate the magazines, charge the firearm, etc.), they are ideal for people with disabilities. They are also ideal for people with arthritis and the elderly.

 

Disadvantages of Semiautomatic Firearms for Self-Defense

1. Medium and high-powered calibers can penetrate walls or barriers, potentially endangering people on the other side of those walls. Using specialized ammunition like hollow-points or frangible rounds can reduce this risk. See our blog on this subject here.
2. Semiautomatics are inherently more mechanically complex than some other manual-action firearms, thus needing regular cleaning and proper lubrication to avoid malfunctions. This added maintenance may be a drawback for some.
3. Semiautomatics, especially rifles, are often unfairly associated with criminal use due to media portrayals. This stigma can influence public opinion and policies, complicating ownership for responsible users.

 

Colorado Senate Bill 25-003 – A Ban on Semiautomatic Firearms

Colorado’s proposed Senate Bill SB25-003 is a direct attack on the ability of law-abiding citizens to defend themselves with commonly owned semiautomatic firearms. The bill would ban almost all semiautomatic rifles and shotguns that accept detachable magazines and gas operated semiautomatic pistols. These firearms are typically the most popular for choices for many lawful purposes including self-defense. Despite the tortured language the bill’s sponsors use to conceal SB25-003 as a continuation of the 2013 15-round magazine limitation and not an “assault weapons” ban, it is in fact a broader de-facto ban on commonly owned semiautomatic firearms. 

Unlike other state ‘assault weapons bans,’ which define an ‘assault weapon’ based on specific cosmetic features like a pistol grip, barrel shroud, or bayonet lug, SB25-003 takes a broader approach by banning nearly all semiautomatic rifles and shotguns that utilize detachable magazines. This includes popular hunting rifles such as the Browning Automatic Rife (BAR) which typically come with 4-round magazines. Under this bill, many popular firearms, including AR-style pistols and rifles, would be prohibited, making it far more difficult for Coloradans to obtain the tools they need to protect themselves and their families.

This legislation is not only misguided but also blatantly unconstitutional. Semiautomatic firearms are some of the most widely owned and commonly used guns in the country, which the U.S. Supreme Court has repeatedly affirmed are protected under the Second Amendment. By targeting these firearms, SB25-003 violates the fundamental right of Coloradans to keep and bear arms for lawful purposes, including self-defense.

 

The Importance of Self-Defense Legal Protection

What you don’t know can land you in serious legal trouble. Not every District Attorney or law enforcement officer will recognize your right to self-defense, and a prosecutor driven by ideology or ambition may file criminal charges against you even if the police agree you acted in self-defense. Even if you’re acquitted in criminal court, you could face a civil lawsuit from your attacker’s family. These situations aren’t hypothetical—they’ve happened to people just like you.

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Just as a quality semiautomatic firearm can save your life or that of a loved one in an emergency, having self-defense legal protection can safeguard your future. Ask yourself these questions, and if you answer “no” to any, it’s time to seriously consider legal protection:

• Do you have a skilled attorney on retainer for criminal defense?
• Can you pay legal bills out-of-pocket without an unlimited budget?
• Do you have $100,000 in cash for bail that you can afford to lose?
• Can you access professional counseling for post-incident trauma?
• Are you protected against civil suits that could force you to sell assets like your home or car to pay a judgment?

 

Second Call Defense Has Your Back

Second Call Defense has a 100% success rate defending our Members with unlimited legal defense protection for both criminal and civil cases. We act as soon as you call us, and can help you stay out of jail and protect your legal rights. We ensure that you’re never alone in the aftermath of a self-defense incident and we will never ask you to pay us back for your legal defense.

Immediate up-front self-defense legal protection from Second Call Defense is your protection against reckless prosecution and spurious civil suits. The use of any form of self-defense can get you arrested, prosecuted, and convicted without proper representation.  We cover all incidents of self-defense, whether you use your hands, feet, a knife, rock or a firearm.

With Second Call Defense you have an UNLIMITED legal defense budget for both criminal and civil suits.

READ MORE: When It’s Too Late to Buy Self-Defense Liability Protection

 

Join Second Call Defense Today

Second Call Defense has a 100% success rate defending our Members. We ensure that you’re never alone in the aftermath of a self-defense incident and we will never ask you to pay us back for your legal defense. Click here to become a Member of Second Call Defense.

*Second Call Defense is not insurance and does not sell or promote insurance products.  Second Call Defense is a membership organization that provides its members access to the “Second Amendment Support Foundation, Inc.,” which provides the means necessary to protect Second Call Defense members from the legal aftermath of exercising their right to self-defense. For an overview of the differences between Second Call Defense Member Benefits and traditional insurance, click here. 

 

Conclusion

Semiautomatic firearms are an ideal option for self-defense. They offer speed, reliability, and adaptability and come in many caliber options across rifle, shotgun and handgun platforms. When coupled with detachable magazines, they are a formidable defense against perpetrators that may seek to do harm. Unfortunately, some states have restricted access to some semiautomatic firearms and Colorado’s SB25-003 would be arguably the worst gun ban in the nation if it becomes law. This bill not only undermines the Second Amendment but also disregards the real-world needs of those seeking to protect themselves and their families.

Just as owning a quality firearm is critical for self-defense, having self-defense legal protection, like that offered by Second Call Defense, ensures that you are fully supported in the aftermath of any incident. Your safety—and your future—deserve nothing less.