Here is a custom KTR I put together. Shooting at 1.15 joules with .3s (thats 350 fps with .2s) Takes AK mags as well as MP5 mags. The adapter can be removed by pressing the AK mag release. Internally, it is mostly cyma OEM parts. Cylinder was swapped for a non ported cylinder. Avengers Derlin nozzle with O-ring. Arcturus High torque Neodimium motor. LT aluminum hopup chamber. LCT bucking. Externally has a matrix/cyma grip. Charging handle knob. Steel birdcage flash hider to complete the KTR look. LCT steel selector. I personally sandblasted and painted the body. $260, I cover shipping expenses.