The purpose of the G302/G303 spring buttons is to reduce the pre-travel distance..this can be accomplished with a spring OR, by making the button peg longer..
We did something similar back in the day, 20 years ago.
You can do this on ANY mouse..
How do we make the peg longer ? Just put a few pieces of tape on it. we're talking less than a millimeter thicks'worth here..
For example, if you have a G502 which doesn't have the spring load, to achieve the exact same --responsiveness-- as the G303..
YOU WOULD...vvvvINSTEAD OF the G303 below