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AR-15 Parts, Accessories & Attachments  

Whether you’re building an AR-15, working on a repair, or performing an upgrade, we have all the parts, accessories, and attachments you need at Geissele Automatics. 

 From AR-15 uppers and lowers to barrels, magazines, and more, all of our firearm components are manufactured in-house to ensure the highest quality and unmatched durability. 

Explore our selection and find exactly what you need to enhance your rifle’s performance, increase shooting accuracy and comfort, and customize your AR-15 to make it your own with Geissele Automatics. 

AR-15 Lower Parts 

The lower receiver of an AR-15 houses key components of the firearm, such as the trigger, magazine catch, magazine well, safety selector, and buffer tube. These all play a crucial role in firing and controlling your firearm.  

Lower Receiver & Receiver Sets 

A complete lower receiver on an AR-15 includes the trigger, magazine catch, bolt catch, safety selector, and buffer recoil system that contribute to the function of the firearm.

 At Geissele Automatics, you get the best of both worlds with the Super Duty Receiver Set which includes a stripped lower and upper receiver. 

The set is precision machined from 7075-T6 aluminum forging, finished in sturdy Type 3 hard coat anodize and capped off with a laser engraving of SAFE/FIRE markings and T-marks, making it the ideal start for your high-quality dream build. 

Lower Parts & Lower Parts Kit 

Explore our extensive selection of high-quality AR-15 lower parts, meticulously designed to optimize your firearm's performance and reliability. 

Our collection encompasses a wide range of key components, from trigger guards to safety selectors and beyond.  

  • Safety Selector 

Located on the side of an AR-15 rifle’s lower receiver, a safety selector allows you to engage or disengage the firearm's safety mechanism. 

The Geissele Super Configurable Safety, made from stainless steel with anti-corrosion properties, is an ambidextrous replacement for the mil-spec safety in your carbine. 

To ensure the levers are secured, a spring-loaded plunger holds them in place.  

The retained plunger reduces the risk of losing an attachment screw and ensures that the levers remain anchored during rigorous use, cleaning, or servicing of your carbine. 

  • Trigger Guard  

A trigger guard is a protective component found on firearms, providing a barrier against accidental discharge. It is a loop or ring-shaped structure made from metal or durable polymer, located directly around the trigger area. 

At Geissele Automatics, you can protect your trigger and prevent unwanted firing with our trigger guards. 

Precision machined and finished with the best care, our trigger guards feature rounded edges and provide a significant ergonomic advantage over a straight mil-spec trigger guard. 

  • Bolt Catch 

A bolt catch holds the bolt carrier group (BCG) in the open position after firing the last round of the magazine. It is located on the left side of the AR-15.  

Built with war fighters in mind, the Geissele Maritime Bolt Catch works with any lower receiver designed to accept a mil-spec M16/M4 Carbine bolt catch.  

The expanded surface area helps facilitate the process of locking back or releasing the bolt when changing the magazine.  

Ideal for left-hand shooters, the extended controls can help you make magazine changes easily and lock the bolt back faster. 

Complete the high-end look of your carbine with our takedown pins, mag release buttons, and mag catchers.  

Lower Parts Kit 

Whether you need to rebuild or complete your lower receiver, look no further than the all-in-one Geissele Standard Lower Parts Kit. 

The kit includes all the necessary components you’ll need, from bolt catches and the Ambidextrous Posi-Lock to trigger guards and beyond. 

Machined from stainless steel to provide an extended life span, there is little opportunity for your lower parts to rust or fail — whether in extreme conditions or under heavy use. 

Buffer Tube  

A cylindrical tube located at the rear of the AR-15 rifle’s receiver, a buffer tube serves as a housing for the recoil system and as a mounting point for the buttstock. 

A buffer tube contains a spring and a buffer, which work together to absorb the recoil generated when firing a round. 

 At Geissele Automatics, our buffer tubes are built to adhere to the strictest mil-spec standards, boasting 6 versatile stock positions. 

 Proudly made in the USA, this carbine-length Premium Buffer Tube showcases a mil-spec diameter, weighing a mere 3.7oz — the ideal match for your AR-15 lower while maintaining compatibility with a majority of top-notch mil-spec diameter AR-15 stocks. 

Super 42 Buffer Spring 

Located inside the buffer tube — which is attached to the rear of the AR-15 rifle’s receiver — a buffer spring cushions the impact of a firearm’s recoil. 

The Geissele Super 42 Spring enhances your AR-15 pattern rifle's performance and reliability. 

Inspired by the German MG42 Machine Gun, its innovative triple-wire design functions as an energy absorber and harmonic damper, enabling the springs to flex independently from each other.  

Experience a 15% stronger average return force, ensuring smooth operation even in a dirty firearm or when utilizing steel-case ammunition. 


A buttstock is designed to be held against your shoulder, providing a stable platform for aiming and firing. It is attached to the rear of the firearm, just behind the lower receiver.  

A stock can be either fixed (to accommodate heavier front ends) or collapsible (allowing the length to be adjusted).  

Equipped with a cheek weld, a buttstock can accommodate a wide range of shooting positions, such as standing, sitting and kneeling. 

At Geissele Automatics, we have a wide range of stocks that deliver the similar strength and stability of a fixed stock, together with a consistent and comfortable cheek weld in any type of position. 


A grip is a handle that is attached to the rear of an AR-15 rifle’s receiver. It provides you with a comfortable and ergonomic grip to gain better control of your firearm while boosting accuracy. 

From classic grip angles to vertical foregrips and beyond, our grips are equipped with finger grooves and checkering for exceptional ergonomics. 

AR-15 Upper Parts 

The upper receiver group attaches to the lower receiver to form a functional AR-15.

The upper parts include the upper receiver, barrel, bolt carrier group (BCG), and charging handle. 

Charging Handle 

A Charging handle, also known as a bolt handle, sits inside the upper receiver of an AR-15 rifle. 

 It is used to manually cycle the rifle’s action, moving the bolt carrier group (BCG) rearward — allowing you to shoot by pulling the bolt back and forth to load the firearm. 

Machined from a solid block of aircraft grade 7075-T6 aluminum, our charging handles feature a checkered lever surface, ensuring seamless operation even with gloves. 

Choose from an ambidextrous design for streamlined use from either side of the firearm or one that meets the requirements of special agents from the Federal Bureau of Investigation (FBI). 

Handguards and Rails

Handguards and rails attach to the upper receiver and cover the barrel to protect the shooter. Modern modular handguards and rails can provide a standardized platform for mounting various accessories such as lasers, flashlights, grips and bipods. 

Made from lightweight and durable materials such as aluminum or polymer, modular rails are designed for easy installation and removal. 

Experience unparalleled performance with our Super Modular Rails. Effortlessly mounted to your AR-15 upper using the advanced Geissele Barrel Nut design, our Super Modular Rails offer exceptional rigidity. 

With anti-rotation tabs and set screws, your Super Modular Rail remains secure and steady, even under extreme conditions. 

 Bolt Carrier Group 

The bolt carrier group is located in the upper receiver, housing the bolt carrier, bolt, firing pin and cam pin. It is responsible for cycling the firearm when you pull the trigger. 

Geissele’s Reliability Enhanced bolt carrier groups boast a torqued and staked, Chrome Lined, Nano coated gas key. 

Crafted from advanced H13 tool steel, the cam pin features Nanoweapon (Chrome-Nitride) coating for optimal corrosion and wear resistance. 

Upper Receiver 

The upper receiver houses and protects the barrel, bolt carrier group, and charging handle. It is connected to the lower receiver, which houses the trigger group, magazine well, and other essential fire controls. 

Geissele Assembled Upper is a high-quality component that comes with a dust cover and forward assist, two key features that enhance the functionality and durability of your firearm. 

With precision machining that meets mil-spec standards and M4 feed ramps, this upper receiver is built for reliability and consistent performance. 

Iron Sight 

An iron sight allows you to accurately aim and shoot your target. 

It is made up of two parts: a front sight and a rear sight. The rear sight is a small notch on the gun, while the front sight is a small post at the end of the barrel. 

The Mbus® Sight is made out of robust Melonited steel. 

It features a positive detent-lockup when deployed and tool-less front post adjustments, so you can zero in on your target and have a low-profile footprint while ensuring compatibility with most rifle configurations. 

Gas Block  

Located on the barrel, a gas block is responsible for regulating gas flow from the barrel to the gas tube. 

The Geissele Super Gas Block is a low-profile gas block designed to fit under most free-floating handguards. 

Precision-cast from 17-4 stainless steel, this gas block ensures outstanding corrosion resistance and strength. It covers Geissele’s own "Bombproof Installation” which utilizes a coil pin to secure the gas block on the barrel, preventing slides or twists under any operating conditions. 

AR-15 Attachments 

AR-15 attachments are additional components that you can add to your AR-15 rifle to enhance its accuracy and overall performance. 

Cold Hammer Forged Barrels 

A cold hammer forged (CHF) barrel is a type of firearm barrel that is manufactured using a specific process that involves hammering a bar of steel into a barrel shape. 

This component strengthens the barrel and withstands heat — improving accuracy and precision. 

The perfect choice for hard-use duty firearms, competition guns, and everything in between, our CHF barrels at Geissele Automatics undergo rigorous High-Pressure Testing (HPT) and Magnetic Particle Inspection (MPI) to ensure accuracy and reliability.  


 A magazine stores ammunition and feeds rounds into the firearm's chamber. It is a detachable component that attaches to the bottom of the lower receiver.  

A magazine is made from metal or polymer and may be single or double-stacked, depending on the caliber and size of the cartridge.  

Built to exact mil-standards, our magazines are reliable and trusted by armed forces from all parts of the globe. 

 Suppressor Alignment Gauge 

A suppressor alignment gauge is a specialized tool that ensures proper alignment between your firearm and suppressor (also known as a silencer, “can” or muffler). 

It verifies and adjusts the alignment of the suppressor to ensure that the bullet passes through the center of the suppressor's baffles, reducing sound and recoil. 

The Geissele SAG is crafted from hardened steel, ground 0.002" below the nominal bore diameter, and finely finished, to resist wear from abrasive powder and prevent corrosive particles from sticking on its surface.  

Gunsmithing Tools 

Whether you’re an expert AR-15 builder or a budding firearm enthusiast, count on our gunsmithing tools for your repair, modification, and construction needs. 


A firearm lubricant is a special type of oil or grease that reduces friction and wear between the moving parts of a firearm. 

 They are designed to provide a protective barrier, reducing heat buildup and preventing rust and corrosion by repelling moisture. 

Ensure your firearm seamlessly operates even in the most adverse conditions with our collection of ALG Go-Juice (GJ™). 

The essential quality of a firearm lubricant is its lubricity or "slickness”. 

Go-Juice outperforms military-grade CLP by 500% (as identified in laboratory tests) and consists of oxidation-resistant molecules to prevent gumming — the buildup of residue or debris within the internal components of your firearm. 

AR-15 Accessories  

At Geissele Automatics, all of our accessories are built to enhance your firearm's precision, comfort, and reliability — from rail panels and mounting plates to hand-stop kits and beyond. 

Frequently Asked Questions

The common parts of an AR-15 include the upper and lower receivers, lower parts, barrel, bolt carrier group, buffer spring, buffer tube, charging handle, trigger assembly, and magazine. These parts are responsible for firing and cycling rounds, as well as controlling recoil. 

Common attachments of an AR-15 include muzzle devices such as flash hiders, compensators, and suppressors that help reduce flash and recoil.  On the other hand, hand guards, buttstock , and pistol grips are utilized to improve ergonomics and handling. 

The lower receiver is the only component of an AR-15 that is classified as a firearm. It houses the trigger mechanism, which is responsible for the firing, as well as other essential components. 

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