Oodalump's guide to performance K'nex guns
I just think this needs to be brought up again and seen some more. Lots of very useful information in here for both new and experienced knex gun builders. And no this is not outdated, do not look at the post date. That is irrelevant. Here you go, read through all of it. All of it.
This guide helped me a lot, and should help everyone else as well.