The AR-15 lower parts kit is a vital piece of an AR-15 that includes the trigger, hammer, bolt catch, trigger guard, magazine catch, magazine catch button, takedown pin, takedown detent spring, and several more components. If you are looking to build an AR-15 you will need the lower parts kit in order to finish your 80% lower receiver. Many AR-15 operators choose to upgrade their lower parts kit to help provide a smoother trigger pull and a tighter shot group. The last thing you want at the range or in a defensive situation is for your lower parts kit to fail and cause your AR-15 to not fire or release the magazine.
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Showing 1–24 of 56 results
A lower parts kit comes in a variety of types ranging from a standard kit to a drop-in kit and even a field repair kit. The type of kit you need will depend on the purpose you need it for so we will briefly discuss the types of parts kits available.
The standard parts kit comes with all the necessary parts to finish your lower build. Parts are typically standard, Mil-Spec (unless noted) and will include the fire control group, pistol grip, safety selector, trigger guard, and all the necessary pins and springs.
The enhanced parts kit is much like the standard kit because it will come will all the necessary parts that are needed in completing a lower. The main difference is the enhanced part or parts that could range from an upgraded fire control grip to a more ergonomic pistol grip.
A drop-in kit is usually all the parts needed minus the fire control group. This parts kit is designed for those that have a drop-in designed trigger and only need the additional parts to finish their lower. Another version of a drop-in lower parts kit is one that includes an actual drop-in trigger as well as the other parts needed for finishing.
A repair, field, or G.I. kit is designed to give you a number of spare parts and typically is used for throwing in the range bag. These types of kits come in handy when a spring snaps or a pin breaks. Always a good idea to have in hopes that you never have to use it.
Keep in mind that lower parts kits can come with or without certain parts or part groupings for your lower receiver. A standard kit comes with all the parts needed for your receiver while a drop-in kit may come with everything but the trigger assembly. Kits are designed for different purposes and fluctuate in pricing to accommodate what may or may not be included. To get a better understanding of a lower parts kit, lets take a look at the parts that would come in a standard or enhanced kit. Based off what you’re AR-15 build setup looks like will depend on what parts you need.
The trigger assembly is one of the more common upgrades that shooters end up making. It’s made up of your hammer, trigger, and disconnector and provides the firing action within your rifle. Common upgrades of the trigger assembly include installing a drop-in trigger or replacing the trigger with a better one.
The pistol grip is a standard part of the AR-15 and is the part that your shooting hand holds while firing your weapon. It is another common upgrade although not quite as common as other parts. For those looking to move away from the common Mil-Spec type of grip, upgrading happens when shooters prefer a more comfortable hold.
For many shooters, the standard trigger guard in a lower parts kit is sufficient enough. Sometimes, though, the need arises for an upgrade. With the trigger guard sitting directly below the trigger and your trigger finger, sometimes having a trigger guard that provides more finger room is necessary. Not as common of an upgrade due to the lack of impact the upgrade has overall.
Magazine Catch and Release
The magazine catch does just what it sounds like - it catches and keeps the magazine secure within the AR-15. The magazine release performs the opposite function and allows the operator to release the magazine when needed. While not common, most upgrades to the magazine catch include a larger catch and release that’s easier to push.
Bolt Catch and Release
The bolt catch sits on the left side of the rifle and provides the operator a way to keep the bolt carrier group open. Once a magazine is installed and the operator is ready to fire, the upper section of the bolt catch is pushed to release the magazine into a closed position. While not common, an upgrade to the bolt catch can make it easier to catch and release the bolt.
The safety selector is a common upgrade for left-handed shooters as well as shooters that prefer an ambidextrous safety or even a push button safety. Another common reason for upgrading the safety selector is when an operator is wanting color coordination with other parts of the rifle.
Being the pins that hold the upper receiver and lower receiver together, they are often upgraded to improve ease of use. If a shooter wants to be able to break the action (separating the upper and lower receiver) quickly, they install an extended rear takedown pin. Another type of upgrade for the takedown pins is to move to a better material such as titanium. Titanium, for example, provides a smoother feel and better fit than the standard pins.
The buffer tube is normally not a part of the lower parts kit. You’ll often find them sold with the buffer and spring or bundled with the with the lower parts kit and stock. The buffer tube is not an upgrade that most shooters think about and only comes into play when upgrading the stock or buffer itself.
Buffer and Spring
Most shooters don’t think about upgrading their buffer and spring to help reduce recoil and improve their rate of fire. There are, however, some buffers available that focus on further reducing the impact of a shot on the shoulder. This provides a higher rate of fire as well as a tighter shot group. The buffer and spring are typically not included in a standard AR 15 lower parts kit.
The butt stock is a common upgrade as it helps provide comfort when firing as well as adjusting to the shooters shoulder. While an adjustable stock is common, some shooters prefer a cheek rest when firing so they choose one that has high adjustability and/or a cushioned rest.