Well, since you say accuracy is more about compression, I am somewhat worried that my gun may be having compression issues. What kind of groupings at say 30-40 feet would you expect running my current setup?
Prometheus 509mm tightbore
Guarder clear rubber
Shredder's concave spacer
And it's shooting at 400 ish FPS (estimate)
Also, do unused bbs deteriorate over time?