A common misconception is that a tighter bore gives higher accuracy, that's not true. For long range shooting, a 6.05mm in a 455mm length is best. There is a thread on here titled 'Inner Barrels Resolved', it should clear some things up about barrels. I have a stock hop up chamber and bucking in my MB06, also made by Well, it works amazingly. Barrel spacers are pretty easy to make. There are probably threads on here that will tell you how to make them, or just look it up on YouTube. As for scopes, what's your budget? Barska and Nikon make good scopes.