Piston vs Gas Impingement AR 15s

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AR-15 for sale

Gas Piston versus Direct Impingement System

Once you have made the decision to purchase an AR-15 you may be wondering whether to choose a gun for sale with a gas piston system, or one with the direct impingement system (DI/DGI). There are pros and cons to both systems, and ultimately it becomes a matter of personal choice. The following provides an overview that may assist you in making your choice between the two systems when purchasing an ar-15 for sale.

Gas Piston Systems


The AR-15 for sale in newer models includes those with a gas piston system. Gas piston systems run cleaner and cooler, contributing to longer service life and less breakage from heat and the resulting wear and tear. This is due to their generally requiring less lubrication. The need for more lubrication in turn contributes to the presence of more grit and grime.

Gas piston systems are by far considered to be the more reliable of the two, especially when chambered with 5.56 NATO in short barrel receivers.

In general, the gas piston system runs a wider variety of ammo with fewer problems than the direct impingement system.

Excluding the proprietary gas piston system, components in general among most major manufacturers are MIL-SPEC and will interchange with the direct impingement system variant weapons.


Many AR-15 parts may be proprietary and not user friendly, or available for user replacement. The gun may have to be sent back to the manufacturer for repair, replacement or upgrades. If you plan to provide your own repairs and upgrades its best to know before you buy a specific brand or gun with a gas piston system, whether or not you will be able to do so.

Guns with a gas piston system are generally heavier than those with direct impingement.

Carrier tilt wear is more likely due to the torque caused by the piston. Some manufacturers have already addressed this issue in their line of guns for sale.
If you use your AR a lot, chances are at some time down the road you will have parts to wear and break.

If sending your gun to the manufacturer or a shop for repair is a something you would prefer not to do, consider that with many gas piston systems you may have no other option when dealing with a proprietary component or AR-15 parts.
Finally, there is a limited number of brands offering the AR-15 for sale with a gas piston system though this will certainly improve in time.



The standard AR-15 utilizes what is commonly referred to as the direct impingement gas operation system. Replacement parts are more readily available, especially with MIL-SPEC AR systems. DI/DGI systems have greater interchangeability between brands providing greater availability of ar-15 parts.

Maintenance, as well as upgrading with a wide variety of available ar-15 accessories is easy and quick for anyone with a working knowledge of guns. You don’t have to send your AR to gun shops or the manufacturer for repair.

DI/DGI AR’s are generally lighter, lacking the extra weight of the piston and need for an extra thick barrel or other upgrades necessary due to the increased torque of the gas piston system.
The large variety of AR-15 parts available from a large number of manufacturers makes upgrading the AR with the DI/DGI easy without having to send it to a gun shop or the manufacturer.


DI/DGI systems generally tend to be less flexible in the variety of ammo that can be used without issues occurring.
In the DI/DGI system gases are blown back into the chamber providing the rifles cycling action. The downside is this cycling action contributes to a dirty gun, requiring more frequent cleaning and maintenance than gas piston systems.

The DI/DGI when used with a short barrel receiver and a suppressor, or in dusty conditions, is more prone to jamming than the gas piston system. There again, requiring more cleaning and maintenance.

In summary, gas piston systems are more maintenance free with a potentially longer service life, but are you willing to send your AR to the manufacturer or a shop for repairs and upgrades? Parts are not widely interchangeable between brands utilizing the gas piston system with few brands available currently. When considering this system, it is best to find out in advance if the brand of your choice has user-friendly parts or requires a professional. Many manufacturers increasingly require all guns be sent to them for any repair due to safety reasons, and will not sell parts even to a gunsmith. This is especially true with the proprietary parts of the gas piston system. Know before you buy.

Direct impingement systems on the other hand are generally easy for user repairs and upgrades. Many parts are typically interchangeable between brands and with wide availability. The DI/DGI system is lighter in weight but will require more frequent routine cleaning and maintenance as well as after a heavy day of firing at the range.

As with any firearm it comes down to personal habit and preference. Your best option is always to fire weapons of both systems on a range before you buy, if at all possible.

GrabAGun.com is the premier online choice of those shopping guns for sale. We have both firing systems available in our inventory of AR-15’s for sale.

We provide discounted pricing, layaway and financing for those browsing online gun shops. Shipments are arriving daily so check back often if an item is sold out, or click on our wish list to be notified of availability. Give us a call and let us provide you with the GrabAGun advantage.

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