[Sevens]

Given that the 12.5 gr loads were hard to eject, I would back off on them. But that's what I would do in the situation.

If you loaded some 12.2 grain loads...
and they gave you similar groups, or even smaller...
and they ejected nicely...
Would you miss the few FPS from a somewhat lighter load?

What's the purpose of the ammo? If it's general target, plinking, fun load, I'd back it off. If it has to be hunting ammo that needs a specific velocity to perform as intended (and you'd need a chrono to make sure you are getting what you want), then maybe not.

Without a chrono, you don't know the FPS difference in your revolver between 12.2, 12.5 and 13.0. If it's 40 FPS, it's kind of pointless to add the wear & tear on your revolver and shooting hand, isn't it?

Reading primers is not a very good way to get a REAL idea of what is happening. It's a reference point, but there are dozens of examples where a hotter, higher pressure load will show less flattening of a primer than a lighter, less pressure load in a different gun or caliber.

Also ask yourself what other guns you have in your arsenal. Have you got a .44 Mag? If yes, then does it make good sense to hot load your .357? (it may, I'm just making a suggestion)

Running the ragged edge is fine for some. It's not my style, and it's definitely not why I reload.