Guide to identifying AR-15 Gas Tube system

There are many who are fascinated with shooting a rifle and would like to know about the different tools and accessories that are available in the market, using which they can have an amazing shooting experience and greater accuracy. One such accessory is the Gs tube AR-15 systems which are available in four main lengths these days, namely, Rifle, Mid, Carbine and Pistol. Each gas system does require varying lengths of handguards and gas tubes. Hence, it becomes crucial to know as to which type is being cruelty used prior to ordering parts for the AR-15. In case, the person is not aware of the type of rifle size that he/she possesses, then simply by measuring the gas tube or handguard length, it is easier to find out the actual size and order accordingly. 

Pistol length

This type of gas system is used exclusively on AR-15 rifles or AR-15 pistols having very short barrels, which is usually around 10” long or even less. Generally, such systems may come with approximately 4.5” of gas tube. For such systems which are in length between 3” to 4”, there are free float tubes or handguards. Low profile gas blocks including carbine length free float handguards are being preferred by many people who like to install them so that they are in a position to have more comfortable and longer forearm grip area.

Carbine length

Such gas system when mixed with barrel lengths, approximately around 10” to 18” perhaps is among the most common of all setups across the different AR-15 rifle types found. Approximately, the carbine gas tubes found are around 7.5” in length. This effectively means that the handguards are around 6.5” to 7” in length. It includes the following:

  • Midwest industries carbine forearm
  • Daniel defence omega quad rail
  • Mako handguard & rails system


These types of gas systems are quite popular and also commonly used along with barrels ranging from 14” to about 20” in length. When used, they do offer longer sight radius, while reducing few wear and tear generally noticed on upper receiver part. 

The mid-length gas tube systems approximately are about 9.8” in length and need handguard, which is about 8.5” to 9” in length. Few choices available for this length type include the following:

  • DB TAC 2 piece quad rails
  • DB TAC free float mid length quad rail

Rifle length

These types of gas tube system generally are around 13” in length and need handguards that range between 11.5” and 12” in length. Usually, they are found on those rifles having barrels being around 20” long and even longer. If trying to find replacement handguards to be used for the rifle length system, then the following needs to be checked out:

  • DB TAC 2 piece Quad rail
  • AR carbon fiber free float tube
  • DB TAC 2 piece quad rails
  • DB TAC free float rifle quad rail

Getting to know about gas tube for ar length size can help to plan ordering the correct one and enjoy the shooting session.