Very well done on your first Boinger fettle. As you say, nowhere as tricky as one might first imagine. Nice and satisfying to be able to do it yourself and you can now rest happily in the knowledge that all is checked and as it should be. Nice to know that if you ever were to need to fix anything, it would be easy.
Many 99s I've come across have cocked and shot smoothly out of the box.
Have you done the anti-galling checks / mods?
Now enjoy.
What pellets have you tried so far? If you haven't done so already, do give the H&N FTT and Baracuda 8s a try.