Silicon grease in cylinder!

Rabble rabble rabble!

I was under the impression that the bb bounced around in the barrel. If it never came in contact, then a tightbore wouldn't make the bb more accurate, only increase the fps. Unless you mean doesn't ie only makes minute contacts?

no, it makes NO contact WHAT SO EVER. AT ALL, in a tightbore.
it happens alot in stock barrels on sewing machine guns with poor compression, you get alot of BB strikes on the barrel and it makes this hard plastic residue inside the barrel thats impossible to clean out. I've seen it happen at 200,000 rounds and at 60,000 rounds. But my 249 has always had great compression, at 200,000 rounds I still have no plastic residue in my stock barrel, which means the bb never strikes the side.
In stock barrels that are poorly manufactured, the bb bounces, thats why getting a tightbore, that's tighter (so air has more trouble escaping around the BB), and more consistent (so theres no bumps on the inside wall), makes it more accurate :)
Accuracy and range is all about getting the proper compression, because with the proper compression, your BB stays in the exact center of the barrel, not touching the walls, all the way down the barrel.

Keep in mind that WD-40 is not actually a lubricant it is a solvent and should be treated as such. If you want to clean your inner barrel with WD-40 your welcome too, but keep it away from your hopup. Run a cleaning pad with a light spray of WD-40 on it through, then run clean dry pads through until they come out clean.

Doing so will keep it clean but if you over do it could result in the hopup failing eventually.

Also keep in mind that a barrel has no moving parts it does not require lubrication, just proper cleaning and maintenance to ensure that any residue as well as dirt and debris are cleaned out.

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?

Thanks guys

Why don't you take it to a gun-doc if your worried? I know I was more than able to install all my upgrade parts but it did take a bit of time to ensure all the pieces were compatable and properly sealing in the respective places. Some times another set of eyes is the best thing for an amature in the whole hobby world.