Airsoft Designs shows how to put together the RK-1L. This is a spring-powered airsoft grenade designed to be loaded with BBs and actuated on impact. It uses a standard AEG spring, tested with an M120, and features two separate chambers, each capable of holding up to 140 BBs, though a load of around 80 BBs per chamber is recommended for reliable performance. A side-mounted adjustment screw allows users to tune the impact sensitivity to their preference.

At the core of the mechanism are two pistons, each equipped with positioning pins and corresponding holes to ensure both fire consistently upon impact. The dual-chamber layout distributes BBs across two simultaneous launches, and the pin-and-hole system is what keeps the firing action dependable. Users should note that the design is rated for an M120 spring, fitting a stronger spring risks damaging the internal mechanism.

The RK-1L is built from off-the-shelf hardware, making it accessible to those who want to fabricate their own unit. The parts list includes an M6 nut, M4x12mm and M4x8mm headless screws, eighteen M4 nuts, M3x12mm and M3x6mm headless screws, six M3 nuts, an M120 AEG spring, threaded rods in various M6 and M4 lengths, three 2x15mm rods, and a key ring.