When you say the right fit, I am assuming you mean slugging the barrel and reloading the exact size i.e., no + or-
Thats rarely an issue or necessity unless you have some odd piece with a non-standard bore. If you are shooting a Smith or Ruger, for example, and buy any quality hardcast bullets, of the proper hardness for 44 mag, the standard size will be .430, and they will shoot just fine and do not require gas checks at full magnum velocities. I don't even use gas checks in .454 Casull loads. They tend to be more commonplace for rifle loads.