polished internals

Here is the short summarized version - www.undergroundmodshop.com/forums/vBulletin/showthread.php?t=455

Basically you're removing the overspray on the inside of the gun which causes friction and wear on your internals. This overspray was never meant to end up inside the gun, so some a-5's have a little and some have a lot. Polishing your internals will reduce wear on your o-rings and should give you a slight fps increase for free.

There are several ways of removing the overspray. I would recommend Nevrdull or Mothers mag wheel polish which you can get at walmart, hardware, marine, or automotive stores. Use either a toothbrush or cut up a t-shirt rag. You can skip the nail polish part, just use rubbing alcohol to clean it out a few times when you are done (or getting close). I recommend using rags over a tooth brush because you can put the polish right on the rag instead of the gun, reducing the risk of accidentally messing up the outside of your gun.

My a-5 had a bit more overspray than his and I noticed the performance difference immediately. As blokie mentions, most people avoid sandpaper since you could screw up your gun; however, the metal near my front bolt & cyclone was very rough and actually raised up along with some pits being intented. I carefully removed a bit of that with 1000 grit sandpaper. I did not remove it completely though since some bits were indented and I didn't want to mess up my gun, but now it is very smooth and works perfectly.