LR 300: Американский штурмовой карабин с улучшенной конструкцией.

The Z M LR 300 is an American select fire assault rifle designed by gunsmith Allan Zitta and manufactured by Z M Weapons. The model name LR 300 stands for Light Rifle and 300 is for 300 meters, which is regarded by the manufacturer as the effective range of the rifle with a standard FMJ bullet. The design is based on the AR 15, M16 and C7 rifles, but has a unique semi direct gas impingement system and a folding stock option.

The design was originally a stockless short barreled pistol version of an AR 15 receiver that Allan Zitta used in target shooting competitions. It later went into commercial production as the Master Blaster in 1996. Zitta later developed it into a full rifle with a folding stock, and conversion kits have also been offered for AR 15 rifles. In 2008, the LR 300 was offered under the name Para Tactical Target Rifle (TTR) as a result of a joint collaboration between Para USA and ZM Weapons.

The direct gas impingement system used in the LR 300 is intended to solve the fouling problems of the traditional AR 15 direct gas impingement gas system. The forward mounted return spring also allows for fitting a folding stock, and the factory stock option folds to the left side. The rifle is also available with a fixed stock. Since its introduction, the exterior design has evolved and changed a couple of times. LR 300MLs have flat top receivers with Picatinny rails, allowing them to be used with multiple types of sighting systems. The trigger, forward assist, magazine release and bolt hold release are identical to those of the AR 15. The barrel has a 1:9 inch (230 mm) twist ratio, is chrome lined, and the muzzle is fitted with a Phantom flash suppressor.

The weapon was originally designed with select fire, offering the option for semi auto, full auto, and burst fire options. When fired, the LR 300 has a built in counter recoil mechanism which helps to off set muzzle rise, decreasing the recoil in comparison to the inspiration for the rifle, the M16.

Contrary to the original AR 15 rifle design, the LR 300 has the capability to use a fully folding and adjustable skeletal stock. Most AR 15 rifle variants have a thick, cylindrical recoil buffer tube, more properly called the receiver extension, that protrudes approximately straight back from the rear of the receiver, and the firearm cannot operate without it. This normally precludes the use of anything but fixed or telescoping stocks. The LR 300 however uses a forward mounted return spring which removes the need for a receiver extension.

The LR 300 uses a modified version of the AR 15's standard direct impingement gas operating system dubbed delayed impingement gas system.

LR 300 ML A: Military/law enforcement model (selective fire version). Has an barrel, aluminium forend, and fires single shots or bursts. LR 300 ML N: Military/law enforcement model (selective fire version). Has an barrel, Nylatron forend with attachable Picatinny rails, and fires single shots or bursts. LR 300 SR A: Sport rifle model (semi auto fire version). Has a barrel, aluminum forend, and fires single shots. LR 300 SR N: Sport rifle model (semi auto fire version). Has a barrel, Nylatron forend with attachable Picatinny rails, and fires single shots. LR 300 AXL: Aluminium quad handguard. LR 300 AXLT: Aluminium partial handguard. Aluminium handguard partially fitted with picatinny rails on bottom and sides at 90 mm (3.5 inches) of its length. TTR XASF: Aluminium handguard partially fitted with picatinny rails on bottom and sides, fixed stock. TTR XN: Nylatron handguard.

The rifle can be seen and used by the player in the video game Rust. The rifle can be seen and used by the player in the video game S. T. A. L. K. E. R.: Shadow of Chernobyl and its sequels. In video game Payday 2, a rifle named CAR 4 can be equipped with attachments that make it heavily resemble the LR 300.