So, which one will you pick? To find the answer, we need some ballistic data. Or, you can still enjoy high accuracy by sticking with a shorter barrel which provides subsonic performance. With the right barrel length, your AR9 can reliably reach out and touch targets at 200 yards or more. A rifle or pistol that can shoot both supersonic and subsonic.

A subsonic shooter with a suppressor for quiet shooting.A high-velocity shooter for maximum distance.And that means your AR9 can function as one of three things: 223 Remington are exclusively supersonic cartridges, 9mm perfectly toes the line between supersonic and subsonic ammo. AR9 Ballistics and Barrel Lengthīuilding an AR9 is quite difference from building an AR-15 not because of the different parts, but because of ballistics. Dimensionally, the 9mm buffer is physically the same as an AR-15 buffer. If you're shopping by weight, you'll need a 5.5-ounce buffer. Most buffers designated for 9mm are advertised as simply '9mm buffers' or 'pistol buffers'. The only difference is the buffer itself: To handle the additional force created by blowback gas operation, a heavier buffer is required. Lastly, the AR9 also uses a regular AR-15 buttstock and recoil spring. Most AR9 bolts do not have serrations for using the forward assist, so a 'slick-side' upper may be used without losing any functionality. This is why the AR9 BCG needs a sled where the gas key normally resides: It must keep the bolt carrier aligned with the hammer and barrel. The AR9 still uses a stripped AR-15 upper receiver. Many parts are still interchangeable between the AR9 and AR-15. Since blowback operates the bolt, there's no need for a star chamber or gas port on the 9mm barrel. Obviously, the AR9 uses a different barrel and barrel extension than the AR-15. The dedicated AR9 lower instead uses a custom mag well. A box conversion consists of a metal device that rests inside the magazine well, which retro-fits the AR-15 lower to accept 9mm handgun magazines. That requires the use of a device called a box conversion. He AR-15 lower receiver is capable of being converted to fire 9mm rounds. Instead, a 'sled' replaces the gas key, which serves to keep the bolt aligned with the lower receiver and barrel inside the upper receiver. AR9 and AR-15 bolt carrier group parts are not interchangeable or compatible with each other. Since there is no gas tube required to cycle 9mm rounds, the AR9's BCG (pictured right) doesn't have a gas key. These AR9 parts are different from the AR-15's parts. The barreled upper you'll be building or buying must also accommodate a different bolt carrier group to function with this new method of gas operation. That means your AR9 build will sport no gas tube and no gas block. Gas doesn't travel down a gas tube and into the carrier like a normal AR-15. That means the gas produced by the 9mm cartridge forces the bolt carrier group backwards directly. Like we said, the AR9 operates with blowback. The AR9 is similar to the AR-15 in overall look and feel, but functionally it is quite different. Here's your AR9 Build and Ballistics Guide. If you want to master this new caliber and build another AR to shoot it, keep reading. This blowback-operated variant ditches the gas system and some other important parts are modified. With new developments by major manufacturers like PSA and Anderson, the 9mm pistol-caliber carbine ('PCC') dubbed the AR9 has become a popular alternative to the typical black rifle. The AR-15 platform is no longer reserved for the typical 5.56 NATO and.

9mm ar pistol