Well, I've got a pair of '60 Army's ( Uberti's) that have Kirst 45acp cylinders in them. The first one of the pair was the first 45acp to hit the range for Walt. Since the beginning ( second trip to the range) I've always included 20 rounds of acp+p 's. It puts a smile on your face you can't wipe off !! I don't do it to test the cylinders, I do it to test the platform. I built these specifically to be testbeds for the platform. I have a Pietta '60 Army with a Kirst 45C cyl which I will be testing some "acp" pressure rounds (21,000 psi) as a testbed specifically for Pietta's.
Also, I'll be sending some +p rounds (23K psi) down range in my Dragoons ( 45C) which also have been fitted with Kirst cylinders.
So, that's what I have been / will be shooting in my open-top revolvers. All of these revolvers are set up with close tolerances with a tight.002" endshake, corrected arbor length and captured wedge driven in ( "captured" is a setup I've used for all my wedges and some customers which insures they can't come loose while shooting).
As far as Uberti's factory '71/'72 Open Top , I have never owned one in 45C but I've tuned a few and the cylinders are SCARY thin!! That being the case, I'm not sure I'd push them to a regular diet of 21K psi loads ( if at all, even though they are proofed to about that) mush less 23K!! But, I'd feel perfectly safe with any tier 1 loads in them.
Mike