45 colt problem

[TX Nimrod]

Are you talking about bore diameter or throat diameter? If the bullet is soft enough it will slug up and work fine. Too hard and it may lead. Best to be equal to or greater than the throats.



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[Pathfinder45]

Pathfinder, would that happen if your .45 Colt was .452 and you shot .451 bullets?

If your cylinder throats were .001" larger than your bullets and you were shooting jacketed bullets you would probably not notice anything unusual except perhaps darkening of the cases from propellant gases as the case probably would not have expanded fully until the bullet entered the barrel. With a lubricated lead bullet it would probably be a bit messier. But you were only talking about .001" loose. Now suppose those cylinder throats are .454" or even .456" and it's not hard to imagine that a lot more hot gases are getting around that bullet before it gets to the barrel and it will do marvelous things to make your revolver shoot groups that resemble patterns printed by OO buckshot fired from a sawed-off shotgun.
But if you have nice minimum size chambers with .452" throats shooting .454" lead bullets and your barrels groove diameter is the same or perhaps slightly tighter diameter as the cylinder throats, say, .451", then everything is going to work out a lot better. Upon ignition, the bullet will move forward and squeeze into the throat before it fully leaves the case; the pressure will rise to rapidly expand the case since none of it can get past the bullet. with under-size bullets the gas not only gets past the bullet, it also flow backwards around the case until it expands enough to seal the chamber as the pressure rises higher when the bullet enters the barrel.
I prefer home-cast bullets and like them much better than jacketed. However, jacketed bullets are more forgiving of an undersized bullet.
I'm right now looking at a box of fired 45 Colt cases I shot last week using both 255 grain hand-cast & lubed, and 240 grain jacketed Sierra bullets; all with 9.0 grains of Unique, fired from a Ruger Vaquero...and they all look remarkably clean and shiny.