RE: Porpoising arrows
I don`t exactly know how it affects arrow flight. My nocks were a little too tight when I first got my new bow and the arrow flight was a bit erratic until the bugs got worked out. But I was also tinkering with a bunch of other stuff besides the nock fit, too. The arrow should clip snuggly onto the string. You should still be able to point the bow at the ground and sharply tap the string and the arrow should fall. Or so I have been told.
Good luck.
The Mouse