I have an ASG Dan Wesson 2.5 inch revolver and let me tell you, it is the most satisfying thing ever when you get a hit with one when you know you only have 6 shots.
Like Happy stated, you will need to downgrade them because they shoot around 430 fps from the start (remember they used to be hunting pistols for game,then they got converted for airsoft).
You can easily sort this by getting downgrade shells, which let 50% less c02 get the the bb itself, therefore reducing fps by half, enabling the revolver to be allowed to use in skirmishes.
You get 6 high power shells with it, I purchased 25 downgrade shells for it and they work great.
The good thing about ASG DW's is that when you strip them, you can access everything and you can mod them to be more powerful (although it is not recommend if you want it to be skirmishable) and they are easy to maintain and clean.
The build quality is amazing and second to none, I was truly impressed with it.
Only problem is they are a pain to reload if you have gloves on, its a right fumble but its a great feeling.
I mainly load 6 shells in and use it as a last resort while using my AEG or for getting those tight shots for when my AEG is too big.
The c02 consumption is really good as well.
Overall, like Happy stated, they are a novelty weapon, but they are great fun if you want one, just get some downgrade shells for them.