The buttless assault rifle is a new type of firearm that represents a significant revolution in assault rifles. It abandons the traditional stock and places the grip and trigger in front of the magazine, transforming the traditional assault rifle into a buttless shoulder fired individual automatic weapon. In this issue of "Weapon Control", we will introduce three types of unshielded assault rifles. The FN F2000 Assault Rifle is manufactured by the Belgian company FN and is a compact 5.56mm buttless rifle with a high-tech appearance. The gun body uses a large number of plastic components, and a Picatinny guide rail is installed above the receiver to accommodate optical sights. The gun mechanism adopts a short stroke piston transmission system with adjustable gas flow, allowing the gun to freely switch between semi-automatic and fully automatic modes. The gun is equipped with a 1.6x optical sight by default, making the target image clear even in dark weather. After shooting, the arm system of the gun will fix the empty cartridge case and make a reverse motion to lift the cartridge case up, making way for the next bullet to be fed. It is this rocker arm system that solves the problem of left and right ejection of unshielded rifles. The fire control system also has a distance correction button on the top of the frame, which has programming capabilities and can be matched with 6 types of 40mm grenades. It can also be programmed to adapt to future improved ammunition. Although the F2000 with its own fire control system is more advanced, its high price, heavy weight, and pickiness towards bullets have resulted in mediocre sales in the international market. Many marksmen of the SAR-21 assault rifle are more sensitive to buttless rifles because the receiver and chamber are placed close to the cheek. However, the SAR-21 developed by Singapore adopts a patented safety device to prevent shooters from being injured in low probability events such as shell or bore explosions. The first component of its safety system is the forged alloy steel plate, which is placed directly below the cheeks to protect the shooter's face. The second component is the opening of a vent hole on the sleeve, which can guide the discharge of gunpowder gas in the event of primer explosion or shell explosion, keeping it away from the shooter's face. This well-designed security system basically eliminates the potential safety hazards of self harm. The gas regulator of SAR-21 can be adjusted without the need for tools. Simply lift the gas regulator out and rotate the adjustment knob to adjust it. The head of the machine is a traditional rotary structure, with two locking protrusions in the locking grooves of the locking sleeve, resulting in minimal stress on the gearbox. However, the firing rate of this gun is slower than that of similar firearms, which has affected its sales in the international market. KH-2002 Assault Rifle Iran's KH-2002 Assault Rifle began development in 2003 and was first made public in October 2004. The KH-2002 adopts a modular design concept, and the barrel length can be converted into standard assault rifles, short barreled assault rifles, and long barreled precision shooting rifles by replacing the barrel, making its applicability more extensive. KH-2002 can be flexibly adjusted according to different mission requirements and combat environments, and has strong lethality in medium and long range shooting. It can be paired with bipods and bayonets, increasing its tactical flexibility and practicality. However, the modular design of the gun is not particularly ideal, and the bottom of the gun body cannot be equipped with lower mounted equipment such as grenade launchers, which has a certain impact on its widespread use on the battlefield. (Lai Xin She)