There was a thread here a few weeks ago talking about whether or not it is possible to fire 45 Schofield ammo out of a revolver chambered for 45 Colt. To make a long story short, yes it is usually possible, but the rim of the Schofield cartridge, nominally .520 in diameter, as opposed to the nominal 45 Colt rim diameter of .512, can sometimes cause problems in cylinders with close clearances around the cylinder ratchet star.
I was shooting a Cowboy Action Shooting match a few weeks ago. I normally shoot a pair of 2nd Generation Colts, but a pair of Stainless Vaqueros (old model) always comes along just in case one of the Colts breaks a spring. The Rugers have come along for the ride for quite a few years now without being needed, but I was loading up the Colts and saw that one of them was not locking up properly. The bolt was not rising as it should to lock the cylinder. I knew I probably had a broken trigger/bolt spring on my hands.
I ran back to the car and grabbed one of the Rugers. A nice 7 1/2" barreled job that I bought used a bunch of years ago for a terrific price. I went back to the loading table where I had left my guns, and started loading the Ruger. Suddenly one of the chambers got stubborn and would not accept a round. I didn't think too much about it, figured I might have a bulged crimp or something. I tried another chamber and it was stubborn, but it accepted the round, I left the other chamber empty and under the hammer as we are required to do in CAS. Shot the stage with no problems.
It occured to me as I walked to the unloading table that I was shooting 45 Schofields that day, as opposed to the 45 Colts that I usually shoot. I like the Schofield rounds these days because it requires a bit less Black Powder to fill them up than it does with 45 Colt. So I grabbed a box of ammo and took the Ruger to the unloading table to investigate. I removed the cylinder and tried loading the chambers with Schofield ammo. Sure enough, one chamber absolutely refused to accept the rounds, and another chamber protested, but allowed me to seat a round. good thing, because if I couldn't chamber five rounds I would be done for the day. I could see from the side that the wider Schofield rim was hanging up on the ratchet star, not allowing the round to seat.
Here is a photo for reference. The cylinder in the center is one of my Vaquero cylinders, the cylinder on the left is an Uberti Cattleman, the cylinder on the right is a Colt. Notice how the ratchet star is 'scalloped' around the chambers on the Colt and the Uberti cylinders, the Ruger cylinder is a less complicated part, just a simple drum shape. That is where the problem lay, just not quite enough clearance on the Ruger cylinder for all the chambers to accept the Schofield rims.
At lunchtime I grabbed my toolkit and grabbed a file. After about fifteen minutes of careful filing, the Ruger now will accept Schofield rims in all chambers. Still have to do the other one.