From a balancing standpoint, the HC as it is now having 6 instead of 8 rounds would have been a bit... undesirable. A revolver would be a great idea, and making it more powerful than the current HC would be a must.
We'd have 15 weak-ish 9mm rounds, 8 middle-strength HC rounds, and 6 omg-so-OP revolver rounds.
For the sake of this example, the 9mm has 30 damage, the Handcannon has 110, so must the Revolver have 190 damage?
I'm not sure what else has damage in the 190 range, but i'm sure that this would be enough to make it a viable solution to life's problems