I have a pair of 3 screw Ruger 45s, both needed throat reaming by DougGuy. In the parts department, there are a couple of 45 ACP cylinders that had been paired with other 3 screw 45s. One of those cylinders fits and functions in one of my revolvers, but both the ACP cylinders have large throats, 0.456" or so. Oh, well, that's one reason I have participated in several group buys for large diameter hollow base bullets.