Whether revolver, rifle, or Contender, the principle is the same. Throat sized bullets preclude leading, and line up the bullet and bore axes so that they are collinear. I usually advise shooters to make their revolver bullets about .0005" smaller that cylinder throats. This is because, with the few 10 thousandths out-of-round that most throats and bullets suffer, there can be interference in chambering in a revolver. This can happen in the Contender also where there is no caming action at action closure.
When I load heavy (300-350 grain) bullets way out into the throat, with heavy charges, in a revolver, I use the .0005" undersize approach. This works well when shooting 8 to 13 BHN bullets at pistol magnum velocities. The snug fit of the bullet not only reduces or eliminates gas cutting, but is also has another important function. It forces the bullet and bore axes to be collinear, thus making the system independent of a sloppy cylinder chamber. Because of the success with this approach, I shoot the heavy bullets most of the time -- that is 300-350 grains in the .45 Colt and 300 or so grains in the .44 Magnum. For instance, my .45 Colt Blackhawk throats are .4345" and I use .4340" heavy bullets.
Since I have thousands of the lighter bullets on hand, I sometimes shoot them too. When I do shoot the shorter 200-250 grain bullets, since the seated bullets do not project very far into the throats, I make them as large as possible, (ala Tom Gray) just so that the finished cartridge will allow easy chambering of the loaded round. Chamber measurements on my .45 Colt Blackhawk, next to the throats, are .4878" which will allow up to about .465" bullets before cartridge diameter exceeds that which will chamber. This chamber diameter is larger than the SAAMI maximum and seems to be pretty typical of the Rugers that I have owned -- sloppy. I use a .460 diameter for these lighter bullets, mostly because I have a .460" swaging die that bumps them to that diameter. I will eventually go to the .465" bullet when I can con a machinist friend to grind and polish out another die for me. Just about any over-size bullet will do well here as long as it will chamber.
For any of the short bullets, to get the very best possible bore/bullet co-linearity, I have found that it is advantageous to partial size the case. This leaves the back end of the (slightly tapered) case at nearly full chamber diameter. That, along with a bullet that is large enough to make for a slight interference fit when chambering keeps the alignment pretty straight.
Notice that revolver chambers have quite an array of transitions from the chamber to the throat. Some are a sharp step while others have transitions that are anywhere from an abrupt taper to a fairly generous one. Those with a sharp step can benefit the most from the short bullet approach outlined above. For the long bullets that reach way out into the throat, the transition shape is not as important.
Incidentally, the .45 Colt Blackhawk bore slugs at .449" so the mismatch is pretty extreme. So much for the old wives tale that oversize bullets will cause leading, extreme pressures, hives, wife beating, and bad breath.
To some, all this matching the ammunition to the particular gun may seem like too much trouble. However, once one has shot that ammo he will never again be satisfied with "store bought" or tossed together reloads. It really does make a difference!