BF,
In factory configuration, you cannot use moonclips. There are good speedloaders available for your gun, however (read: Not HKS), and you will be surprised at how fast and handy you can get with them.
On the other hand, it is possible to have a 66 modified to accept moonclips. I have one so configured, and it is able to shoot either with or without moonclips with equal accuracy and reliability. The operation cost me under a hundred bucks including shipping.
I would try some decent speedloaders, though, before jumping in. What've you used so far?
PS--Okay, wait; you have a PC gun, so maybe I'm wrong. If you can use moonclips, there will be a ring around the outside rear of the cylinder that's raised .022" above the rest of the rear face of the cylinder (where it's been inlet for the moonclips, which are .022" thick). I doubt this is the case, but check, and let us know.