 Springfield Armory M-18 by Air Venturi underlever spring piston pellet rifle operates by means of a spring-loaded piston assembly contained within a compression chamber separate from the gun barrel. A coil spring is used as the power plant main spring. Cocking the gun by utilizing a lever connected to the piston assembly pulls the piston rearward, while compressing the main spring until the rear of the piston engages the trigger sear. When a pellet is placed into the barrel it forms an airtight seal. Pulling the trigger disengages this sear, allowing the main spring to decompress and release its stored energy, pushing the piston forward, thereby compressing the air stored in the pump cylinder. Once the air overcomes the pellet's resistance and the air pressure has risen enough to overcome the static friction and or barrel restriction holding back the pellet, the pellet is propelled forward by an expanding column of pressurized air. This takes place in a fraction of a second. The Springfield Armory M-18 by Air Venturi underlever spring piston pellet rifle employs a two-stage non-adjustable trigger. The trigger is held by a spring and sear. The trigger requires two separate pulls or mechanical actions before the sear can release the firing operation. The trigger causes the trigger to travel slightly. This is the first stage, also referred to as taking up the slack. At the end of the first stage, the shooter arrives at the second stage wall, gradually applying more pressure to the trigger until the sear breaks, which releases the piston and initiates the firing sequence. The Springfield Armory M-18 by Air Venturi underlever spring piston pellet rifle employs two different safety mechanisms. The first is the anti-bear trap safety. This safety prevents the loading chamber from closing while the shooter is loading the rifle. The anti-bear trap safety can be released after loading the rifle by depressing the lever on the left-hand side of the action, allowing the cocking lever to be returned to the closed position and making the rifle ready to fire. The second is the manual trigger safety. This safety is known as a latch safety and is located at the front of the trigger guard. The latch safety is mechanically designed to allow for forward and rearward travel within the trigger guard. When the latch is moved by the shooter to its forward position, referred to as safe, it blocks the trigger sear from moving rearward, thus preventing the firing mechanism to function. When the latch is moved rearward, the block is removed, allowing the sear to be released when the trigger is pulled. This is referred to as the fire position.