All of the Ruger 45 Colts that I have measured were .451 and I opened them up to .452 or .4525. I have herd of .454 throates on 45's but have not seen any myself.
I have mesured several Ruger 44 throats over the years and .431 is fairly standard with a few at .432, if a .430 bullet will drop through you have at least .001 clearance and probably .002 if both are the same you will have to drive it through. I have three 44 Rugers and they shoot reasonably...