Does anyone live in Tucson with g&g m4 blowback gearbox experience? I'm planning to upgrade but I don't have much gearbox experience and I don't want to break the blowback attempting to upgrade it. If so I'll probably meet you at toxic sometime once I order the parts (m120 spring and bore up cylinder kit)

The reason I'm upgrading is because my fps is only around 300 and I'm not sure why the problem is. I think it may be a not so good air seal in the cylinder. I'm had the gun for almost a year now though so maybe it's time to put some maintainence parts in it.

Any advise or help would be appreciated!