We have had numerous questions how to assemble the Moscart grenade type, such as those made by King Arms and Mosquito Molds. Admittedly, it can be tricky! There is a tool available to make things easier, but it is not absolutely necessary if you follow these instructions. When you disassemble the shell, please work on a flat clean surface with no other parts to confuse you. There will be eight (8) ball bearings inside, so be careful not to lose them. One trick is to open the shell working inside a clear plastic bag. In case you managed to lose them already, they are standard 3 mm steel ball bearings.
To assemble, please put the main valve on the front part of the grenade first.
Then, insert the mock primer spring, and push the mock primer into the rear of the main valve, compressing the spring.
You can now insert all the ball bearings in the holes, two in each hole. It is advisable to use grease so they don't fall out.
Then, hold the mock primer down with a pencil, and assemble the aluminum deflector ring and steel lock ring (with the groove inside to meet the BBs. If you let the mock primer out too early, it will simply push the ball bearings out and you can not assemble the shell.
While keeping the mock primer down, slip the casing of the shell (rear part) over the pen, and screw it onto the front part. Be careful not to catch the wrong thread, and do not use force. It should go on easily.
After assembling the shell like this, you may release the mock primer, and it should come all the way to the rear position. It may need a bit of wiggling, but will snap all the way back. The main valve will be closed now, so you may charge the grenade with gas.
The grenade will leak gas instantly when refilled, if the main valve is not reset properly before filling. After shooting the grenade, you may reset the main valve simply by pressing in the mock primer until you hear a click. If a click is not heard, it is possible that the O-ring has jumped out of its groove. Another reset-technique is to gradually loosen the casing, until the primer clicks up. Then, tighten the grenade again. (Do note that opening it too much will cause the bearings to fall out.)