About the wear on your bolt that is totally normal, it actually happens to everyones.
And I don't mean to jump on you guys or anything, but Spyders are great markers. I've had my shutter for almost 2 years now and I have had no problems with it, never even had to replace an o-ring. And with the right barrel and LP setup it's quiet and accurate. And when I get my trigger job done it'll have a light 3/16" pull. How many guns can you say that you've paid $20 and gotten an awesome smooth trigger pull. Now, I'm not saying it'll ever be in the same league as my autococker, but I also paid less than half what I paid for it too. Oh, and something I've heard a lot on the paintball forums is you get what you paid for and kingmans in general cost less than $200 and most tourney markers can cost anywhere froom $400 and up so in a way you are paying for a cheaper less quality gun. So, with all that being said it's not that bad a marker.