*CAUTION: If you are unfamiliar with the function and safe handling of an open bolt firearm such as the AM15, you should seek competent assistance, training and guidance before attempting to fire your AM15 Upper Receiver Conversion Kit.
* Carefully remove all parts from the shipping box. Do not remove them from the plastic packaging until ready to install each part. The parts that are included with the AM15 Upper Receiver kit are shown below with a corresponding number to reference with the assembly instructions.
AM15 OPERATION AND FUNCTION OVERVIEW
The AM15 Upper Receiver .22LR Conversion kit is patterned after the original American 180 .22LR machine gun which fires from an OPEN BOLT, which means that it fires from the bolt in the rearward position like an UZI, MAC or a Thompson. A traditional M16 fires from a closed bolt, meaning that the bolt is mated with the barrel with a round in the chamber, waiting for the trigger to be pulled when the gun is ready to fire, much like almost all modern semi automatic firearms operate.
Open bolt operation of the AM15 provides many advantages that far outweigh the minimal inconvenience of having to swap your M16 lower fire control parts. The AM15 comes with the required Colt Light Machinegun open bolt fire control parts to convert your M16 lower to operate similarly to the Colt Light Machinegun open bolt configuration.
Using the Colt Light Machinegun operating principle, the hammer, trigger, and sear are replaced with similar looking parts. However, the parts now assume a different role in the operation of the firearm. (1) The hammer now becomes the sear, in that it engages the bolt and holds it back ready to fire or it disengages the bolt and allows the bolt to reciprocate while firing. (2) The sear now becomes an actuator for the hammer (which is now the sear). As you pull the trigger, the sear rocks the hammer to either capture or release the bolt. For simplicity and clarity, although the function of the parts change, each part will retain its traditional description for the assembly and operation instructions (ie the hammer is the hammer etc).
The AM15 does not have a moving firing pin. Primer ignition is accomplished by means of a permanently machined firing pin in the face of the bolt. Each time the bolt moves forward, it strips a round of ammunition from the feed block and chambers it. When the round is fully chambered and the bolt can not continue any farther forward, the firing pin crushes the rim against the face of the barrel and ignites the round. Thus it is not possible to chamber a round without firing it using an open bolt machine gun. A round will only be in the chamber when it is being fired.
CAUTION: If you are unfamiliar with the function and safe handling of an open bolt firearm, you should seek competent assistance, training and guidance before attempting to fire your AM15 Upper Receiver Conversion Kit.
STEP TWO provides instructions for the installation of the open bolt lower receiver fire control parts.