I'm thinking of geting a CO2 pistol for some fun, and maybe even doing some of the UBC postals as I've moved house and am quite a way from my nearest rifle club, so the .22 target rifle shooting will become a little less frequent for the time being at least. I've got a long cowshed which would make a great 10m range.

Asking for advice as I don't know an awful lot about them, although I've shot an Umarex/Walther PPK which was great fun.

I like the looks of the CP88 and CP99. What's to choose between them? I think they both have single and double action triggers, and I'm led to believe you can add accesories and sights to both. I also understand the CP99 has a funky magazine type thing for the CO2 canister, so you can unload and make safe without wasting the remaining CO2. Does it work well or piss gas everywhere through the extra joints that I imagine must be required between "magazine" and gun. Does the CP88 have this system as well, or a more traditional arrangement?

And what are the alternatives?

Many thanks,
Hemmers