You may be right but I'd want to see the trajectories numerically integrated and plotted. What I know is that trajectories that hit the L1 point with low velocity will confound your intuition that comes from conics. Here is a recent analysis that considers a range of trajectories launched from a certain point

https://www.sjsu.edu/ae/docs/project-thesis/Ethan.Miller-Su2...

which a student project that has a lot of problems and doesn't consider the possibility of relocating the driver but they are considering moderately high angles of around 30 degrees. Their mass driver is about 500m long in the range that if you want to drill a hole that deep you can drill a hole that deep.

Practically there are other concerns about a moon base, particularly these days people are interested in polar locations. You could possibly run 1000 km of maglev to get to the base of the thing but if you are talking that big you might consider a lunar beanstalk which at least doesn't require a catcher at L1.