Hmm... I had to think about it because it's so fluid and intuitive, but here's how it works for me...
After I fire (right-handed), I transfer the pistol to my left hand, placing my left index finger through the trigger guard at the same time my left thumb depresses the safety. Then I cock the pistol with my right hand, pick up a pellet between my right thumb and index finger and place it on the end of the probe, and close the breech, ready for the next shot.
That's what works for me. I left out the part where I drop the pellet in the dirt, but that's also why I do it the way I do it. I'm a world-class klutz. But so far (knock wood), I haven't dropped the pistol yet. Same method works with my carbine.
I know this doesn't specifically answer your question, but the majority of the populace (and hence their target market) are righties. However I have seen a couple of ambidextrous breeches.