The GP37 is a caseless 37mm launcher that uses fence post pipes as is common for launchers, but is based on a caseless eastern format launcher. The GP37 uses design features of the original GP25 and upgraded GP30. The GP37 uses an electrical ignition and is a rocket that can deploy smoke and flashbangs at great distance despite having a short barrel.

This project was initially released during the primer shortage and used an electric igniter on board the round. The annular ground and center post needed to make the connection would become dirty too quickly and were unreliable on the original release. This new release uses an off the shelf ignition system to ignite visco fuse on the back of the caseless projectiles.

The launcher mounts to picatinny rails and its own proprietary standalone frame based on the Kastet. 

The sights recommended for the GP37 are the M15 rifle grenade sights for the M1 Garand. They are simple sheet metal sights and the elevation adjustment is graduated in degrees instead of set ranges, making it easier for end users to record their load data and point of impact.

More projectiles will be available in the future and more mounting options will be provided depending on their suitability.

I plan to make an AK mountable version that latches on a bayonet lug like the GP25 but I am not an AK person and I am unsure the viability of a plastic mount for such a small metal part that gets that hot.