Sizing bullets

[Broomhandle]

I've noticed that many people size lead bullets according to the barrel size. I have often read that many people size bullets according to cylinder size, which is what I do. For years Colt was finishing chambers on SAA's different from the barrels which led to poor accuracy unless the bullets were sized to the cylinder.
Comments ?

[Litl Red]

Since the bullet sees the cylinder throats first, and will obturate to that diameter if it is soft enough to obturate at all, which makes more sense, to size to the throat or the barrel.

Since sizing to the barrel is defeated by the bullet obturating to the cylinder throats, does it make sense to size to the barrel?

[Blackfoot]

How about using a bullet that is the correct size for the barrel, then reaming the cylinder throat to correct size if needed.  It has worked for me.

Blackfoot

[Navy Six]

Dave Scovill, from HANDLOADER magazine, has done a number of experiments on this subject going back many years. One caliber in particular, the 45 Colt, has been plagued by oversize chamber mouth dimensions due in part to Colt changing the barrel groove dimensions(smaller) but leaving the cylinder chamber mouths the same size(larger) resulting in a mis-match which could/did give the 45 Colt cartridge an undeserved reputation for mediorcre accuracy. In almost every case, Dave found the best accuracy came when he sized lead bullets to the chamber mouth dimension.Upon firing, the bullet base would obturate while still in the cylinder and swage down to correct sized as it made its trip down the barrel. Of course, all this assumes the correct bullet alloy, bullet design,powder charge etc. Colt wasn't the only manufacturer to use these somewhat mismatched throat/barrel dimensions, but point being accuracy improved when sizing the bullet to fit the chamber mouths.
If the chamber mouths happen to be smaller than barrel groove specs, then reaming out the cylinder as you mentioned would definatley be the way to go if top accuracy is desired. Otherwise, trying to get good accuracy from such a combination is likely to drive you crazy and make you think about taking up a different hobby.