In an update by Golo Airsoft, the Maruyama B&T MP9-N gas blowback submachine gun has undergone a serious mechanical makeover. The original out-of-the-box performance left much to be desired, with the gun struggling to feed BBs properly and venting gas like a confused humidifier in even mildly cool weather. To remedy this, the project involved a deep dive into the internals, replacing stiff springs and smoothing out rough burrs on the hammer unit that were causing premature wear after only a few magazines.

The real headline of this build is the custom conversion to CO2 power, a process that proved to be as much a lesson in international relations as in engineering. After being ghosted by a Chinese firm—possibly due to a sudden chill in diplomatic relations, Golo turned to a Japanese company to manufacture a high-strength aluminum expansion chamber. This custom part was designed using specific heat calculations to ensure the gun wouldn’t freeze up, though the cost of specialized tools and materials meant each magazine ended up costing about as much as a nice dinner for two at a fancy restaurant.

By the end of the tuning session, the MP9-N transformed from a stuttering paperweight into a high-speed machine with a firing rate that initially clocked in at a dizzying 26 to 30 rounds per second. After some sensible adjustments to the buffers to bring the rate back down to realistic levels, the build achieved a smooth, reliable cycle that matches its real-steel counterpart. It’s a classic tale of spending a small fortune to make a toy work exactly the way it was supposed to in the first place, proving once again that in the world of airsoft, hobby is often just another word for expensive obsession.