I have a MEC 9000G and want to know what the difference is between the regular charge bar and the skeet special charge bar.

I have never heard of a skeet special charge bar. There are standard, steel, progressive and non progressive bars.

Smaller shot packs better than larger shot, so a bar that's calibrated for #4 or #6 shot will throw a heavier weight of #9, skeet size. Shooting overweight loads isn't allowed at some events, so the skeet bars keep you legal.

http://www.mecreloaders.com/order/ChargeBarPartsList.asp

Bye
Jack