I've been gaming a Skeleton Sidearms 8" revolver (same thing as a Dan Wesson) for over a year now. I modified it to reduce the FPS so it'd be legal for field play and CQB. I can adjust it either way to suit.
The speed loader is for loading the shells into the cylinder. You load the BB's into the shells (one BB per shell), place the shells into the loader and push and twist the knob to lock them in. Then when you load the cylinder all you have to do is get the shells into the cylinder and push down on the loader, the lock will release and the shells fall in.
I also have my trusty 1911 semi auto but rarely use it...I love the revolver. It's ridiculously economical on CO2, especially with the fps turned down. I get well over 100 shots on a 12g cartridge. I usually pack a couple of dozen extra shells pre-loaded to help prevent fumbling and yeah, you have to count your shots...but it certainly is do-able. The accuracy of the 8" barrel does keep it viable.