20mm STRATOS CNC steel bolt for Tokyo Marui AKM GBBR

Patented telescopic dual stage blow back system

20mm cylinder bore x 55mm nozzle travel (original 19mm x 44mm)

Full bolt carrier travel

steel CNC made bolt and cylinder

steel cast made recoil spring holder

high ROF buffer spring standard

steel outer shell optional

PA12 nozzle

2nd batch performs better than below video