Quoting Thijs van Ooij
Excellent lmg, good colour, but I don't really like that crank-action mechanism. If you release the crank the rubberbands will start shooting. The best way to do it is by making a 90 degree angle from the crank and then add a wormwheel, and if you place a gear against that and load the rubberbands onto that gear, you have your mechanism. Less space consuming, yet more efficient.
No, if you release the crank, there is a little part that keeps the gearwheel locked. It's tight enough, so the RB's wount start shooting, but not too tight so it's easy to turn the crank!