In the case of the Peasant Railgun, here are a few threads that I would pull on: * The rules do not say that passed items retain their velocity when passed from creature to creature. The object would have the same velocity on the final "pass" as it did on the first one. * Throwing or firing a projectile does not count as it "falling". If an archer fires an arrow 100ft, the arrow does not gain 100ft of "falling damage".
Of course, if a DM does want to encourage and enable zany shenanigans then all the power to them!