Gunslinger Build (Lv. 10-200)

burst is still more bullet efficient though, and i DONT want my inventory to have only bullets

I use one maybe 1.5 sets of vital bullets at zruns that take roughly 30minutes. That's without rapid fire but even so, that's the only situation you should use rapid fire a lot. In normal training, your ship shouldn't break that often once rapid fire is even a high enough level to outdamage burst.