Direct Impingement vs Piston Driven ARs
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Direct Impingement vs Piston Driven AR
Hey all, we here at True Shot Academy are going to go over direct impingement and piston driven ARs today. The AR-15 is one of the most common rifles in the United States, and they are often available in both direct impingement and piston driven form. Our goal with this blog post is to provide a brief overview of these two types of ARs while delving into traits, features, and pros and cons. Without further ado, let’s talk direct impingement vs piston driven ARs.
What is a Direct Impingement AR?
Direct impingement ARs, often referred to simply as “DI” ARs, utilize a gas tube and gas block to feed gasses into the system. During the firing process, gasses travel through a gas port and into the gas tube via the gas block. The gas tube directs gasses rearward into the action of the rifle, engaging with the gas key at the top of the bolt carrier group. The bolt carrier then travels rearward against the tension of a weighted buffer and spring. Once the spend round is ejected and the bolt has traveled to the rear, the bolt carrier group is sent forward again by the buffer and spring in the buffer tube.
What is a Piston Driven AR?
Unlike direct impingement ARs, piston driven ARs feature a physical piston which facilitates the operation of the rifle. These pistons are generally going to be of either the short stroke variety, with a few long stroke offerings existing as well. Like direct impingement ARs, gasses travel through the bore during the firing cycle. These gasses are then directed into a gas port and guided through the gas block. From here, the gasses engage with a piston system which travels rearward to interface with the bolt carrier group. The piston essentially uses the gasses to physically press the bolt carrier group rearwards and facilitate cycling.
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Direct Impingement AR Pros and Cons
Pros:
- More common and accessible than their piston driven counterparts. One can find direct impingement ARs easily at most places where firearms are sold.
- Generally cheaper and more affordable than piston driven counterparts. Direct impingement ARs utilize an established manufacturing standard and practice, meaning that they are not reinventing the wheel or charging a premium.
- Parts are plentiful and readily available. Direct impingement ARs adhere to established milspec sizing and practices, meaning that one can easily get replacement parts for their AR.
- Less moving parts than their piston driven counterparts. Simplistic design with not much to go wrong. In the event a gas tube or gas tube pin fails, these parts can easily be replaced.
Cons:
- Direct impingement ARs will generally run much dirtier than their piston driven counterparts. This is because the gas tube launches gasses into the action of the firearm, leading to carbon and fouling buildup.
- Generally pickier with ammunition than their piston driven counterparts. This is due to the fact that some lighter loads may have issues reliably cycling the firearm. This is particularly evident when the firearm is dirty and fouled.
- Most direct impingement ARs will feature simple gas blocks which do not allow for adjustment and tuning. To tune the gas system on their rifle, an adjustable gas block from a company such as Superlative Arms must be purchased and added to the rifle if one is not already present.
- Direct impingement ARs are generally more challenging to suppress than piston driven ARs. One may need to do additional tuning when attempting to suppress a direct impingement AR. Direct impingement ARs tend to be gassier than their piston driven counterparts, often warranting the addition of a gas busting charging handle. Additionally, one may need to swap the buffer and spring in a direct impingement AR to help tame the gassy nature of the platform.
Piston Driven AR Pros and Cons
Pros:
- Piston driven ARs are generally going to run cleaner than their direct impingement counterparts. This is because less gas and carbon are sent directly back into the action of the AR with piston driven systems.
- Piston driven ARs are generally less picky with different variations of ammunition than direct impingement systems. Lighter loadings which may struggle to cycle a direct impingement system will likely work just fine in a piston driven system due to the assistance of a piston.
- Generally, piston ARs come equipped from the factory with more methods for tuning and adjusting the gas system. This is typically accomplished with a knob or dial at the end of the piston assembly. These systems will generally feature dedicated settings for suppressed and use in adverse and fouled conditions.
- Piston driven ARs will generally be more suppressor friendly from the get-go than their direct impingement counterparts. The additional potential for adjustment paired with the fact that less gasses are directed into the system enhance the suppressed shooting experience. It should be known that some tuning may be required still depending on the ammunition, firearm, and suppressor used.
Cons:
- Generally speaking, piston ARs are not nearly as common or prevalent as direct impingement ARs are. This is to say that one will find many more direct impingement ARs on the market than they will piston driven ARs. This essentially means that customers will have fewer piston driven AR options to consider purchasing.
- Proprietary in nature. Generally speaking, each piston driven design and system is unique, thus making them incompatible with each other. For example, VKTR Industries piston components are incompatible and unique from LMT piston components.
- Piston driven ARs are generally going to be more expensive than their direct impingement counterparts. This is mainly due to the fact that more specialized tooling, manufacturing, and research has gone into producing piston driven ARs.
- More moving parts and potential for error. More complex systems simply have more potential for failure than simplistic ones.
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Who Makes Direct Impingement ARs?
Currently, direct impingement ARs are produced by a number of manufacturers. These manufacturers include both established and new companies who are producing milspec ARs. Companies include Geissele, Colt, Daniel Defense, Ruger, and LMT to name a few. It is also easy to build a direct impingement AR from parts and components due to consistent adherence to milspec sizing and practices. One could piece together a direct impingement AR by utilizing parts from companies such as Aero Precision, Palmetto State Armory, and BCM to name a few. There are a wide variety of direct impingement ARs on the market, meaning one will have no issue finding one if they are so inclined.
Who Makes Piston Driven ARs?
Piston driven ARs are currently produced by a number of companies. These companies include LMT, VKTR Industries, LWRC, PWS, and Ruger to name a few. As mentioned earlier, the piston systems will generally differ and be quite unique from each other. The unique self-regulating gas piston system found in VKTR rifles will not be compatible with the components in a PWS piston system. Like direct impingement ARs, one will be able to build a piston driven AR quite easily. The upper is the important, proprietary part responsible for piston operation. A piston upper will generally work on a standard AR-15 style lower, meaning one can use an Aero Precision lower with something like an Adams Arms piston upper receiver. While fewer piston driven AR options are on the market, one will be able to find one if they truly want one.
Conclusion
All in all, direct impingement and piston driven ARs are both viable forms of America’s most popular rifle. Both styles of AR have their pros and cons but are ultimately versatile and capable firearms which are well-suited to the needs of shooters of all types. Whether your AR is in
5.56x45mm NATO,
.300 Blackout,
7.62x39, or something else, we here at True Shot Ammo have got you covered. Our wide inventory of
ammunition for sale includes things such as
5.56x45mm NATO ammo and
.223 Remington ammo well-suited for AR use. Whether you have a direct impingement or piston driven AR, we here at True Shot Ammo can get you stocked up. As always, happy shooting.
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