Yeah, any kind of rattle/shakyness in my guns bugs the hell out of me.
I think there was a thread on this before, but if you put some tape along the threads of the cocking handle where it meets the receiver you can eliminate the rattle and noise and still be able to cock it if you want.
The GB tech was a far different story. the spring it comes with is really twangy and if you shake the p90, you can hear the cocking handle spring bounce on the barrel and the body, in addition to the regular rattle like the tm metal handle. I had to wrap a piece of paper along the barrel as like a spring spacer and put a few elastics on each end of the spring so it doesn't twang. some book tape along the edges and rails of the sliding part of the body and now it's quiet and still cockable. Can't have the solidness of a metal body and have it rattle all over the place.
just take a few minutes to see how it works and you'll know where to line it with tape to cut down on the tolerance/rattle.
G'lucks.