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  • Post last modified:October 19, 2023

AR15 semi VS full auto. Many people are new to guns and might be interested to learn about the difference between automatic and semi-automatic firearms.

Let's break them down and explain which one is better and why.

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Semi Auto AR15

An semi auto AR15 is more preferred by many skilled shooters. It's accurate and effective for competition shooting and personal defense.


The trigger system is very simple and there are also many aftermarket AR15 trigger upgrades available. This include single and two stage triggers with various trigger pull weight and designs.

Semi auto AR15 can be purchased with just a regular 4473 background check without additional NFA requirement.

Full Auto AR15 

A full auto AR15 functions as a machine gun. A weapon that can fire more than one shot without manual reloading, simply by pressing the trigger, or is made to do so, must be considered.

Most full auto AR15 feature pretty much the same components as a semi auto AR15, but these additional parts are required:

Auto Sear: This is a crucial component that allows the firearm to fire in full-automatic mode. It engages with the hammer to release it when the trigger is held down, allowing for continuous firing.

Selector Switch: The selector switch has settings for safe, semi-automatic, and fully automatic modes. It controls the firing mode of the AR-15. The full auto mode simply places the auto sear at a different angle so it allows the rifle to fire in full auto with the trigger held

Disconnector: This part works with the auto sear and hammer to ensure the firearm cycles correctly in full-auto mode. It helps reset the hammer for the next shot.

Bolt Carrier Group: The bolt carrier group in a full-auto AR-15 is often designed differently from a semi-auto version to accommodate the automatic cycling of the firearm.


The use of full auto firing is only practical for fire suppression in real world combat scenarios. Full auto is not for precising firing.

While most civilians and firearm enthusiasts enjoy shooting a full auto AR15 for fun. It costs a lot to own a registered machine gun and replacement parts are harder to find.