WARNING: I am not to be held responsible for any damage caused to your marker or any other marker this method or any similar method is used on. (Even though I highly doubt you can cause real harm to your marker, even if you did this for hours on end)
Step 1: Disassembly of the Marker
(Sorry for not including pics of disassembly, but it's pretty easy)
You need these following tools for the entire process:
1/8 inch hex key (mine is in a set)
Flat-Head screwdriver (only if you have a response trigger/cyclone feed/both (like me))
Pliers of some sort (only for removing response trigger)
Steel Wool (I used extra fine)
Tippmann 98 custom (durrr)
Step 2: Further Disassembly
Step 3: Gettin' Down 'n Dirty
First you must remove all lubricants and such from the insides to make polishing a lot easier. That and its good to clean your marker after every time you play by opening it up and giving it a good scrub with the rough side of a wet sponge. Your marker will thank you!
Step 4: Now for the Fun!
The areas you really have to get are:
The rear-section of the marker where the hammer has to slide back and fourth a bajillion times.
The front section of the marker where your paint feeds in so that the little plastic piece that has to slide a bajillion times as well has less trouble.
Polishing these areas with the steel wool will increase the air efficiency and speed of your marker.
Step 5: More Fun!
You must first disassemble the hammer by taking out the charging handle and taking out the small plastic spring guide inside by coaxing it out with your screwdriver or just shaking it out.
It also helps to clean the hammer before hand.
Step 6: The Result
Look at that shine!
Also, small pieces of steel wool may accumulate on the inside of the marker. Clean these out with a good rinse of water.
Step 7: Reassembly
Step 8: Lubricating Properly
If your marker came with a small bottle of lubricant, by all means, use that.
If it did not come with any, i suggest using a pneumatic tool lubricant, it's not petroleum based (so it won't corrode O-Rings) and lets face it, a paintball marker is a nail gun that shoots balls filled with goo.
You must lubricate:
The chamber around the hammer.
The hammer itself.
The front plastic piece (and around it)
And it helps to keep your valve system nice and clean by putting a few drops of lubricant through the ASA into the air lines and shoot a few times with air in the system.
Step 9: End
Congratulations on increasing the air-efficiency and reliability of your Tippmann 98 Custom!