I bought swaged ball for my .45, and now my .50 because I didn't want to buy the casting equipment needed to make my own. I didn't think I would shoot enough RB to justify that expense.
I have used both Hornady, and Speer swaged balls. Both companies make good products, but various LOTS of balls from both companies, over the years were less than desirable for accuracy. I have sorted them by weight and diameter, and have spent a lot of time shooting them off a bench rest.
Sorting both Swaged and Cast Balls produces better accuracy IF you are shooting off a bench rest at targets.
For general off-hand shooting, most shooters can't hold their sights on a target consistently enough to make use of that available accuracy, and sorting the balls by weight or diameter contributes nothing to their groups. These are the majority of MLing shooters, IMHO, and they do just fine shooting what they cast or buy, without worrying about sorting by weight or size.
So, to answer your question, you first have to tell us what kind of shooting are you planning to do. If you are going to be a bench rest target shooter, using an Aperture sight, and a globe front sight, to limit your sighting errors as much as possible, then sorting swaged balls by size and weight will MAKE A DIFFERENCE. How much difference will depend on the rifle you are shooting, the caliber, the quality of the barrel and rifling, and your abilities as a shooter.
If you are going to do mostly off-hand casual plinking and general target shooting at 25 and 50 yard targets at the local club shooting matches, then don't bother sorting the balls.
I know a man in my club who weighs more than 300 lbs., and stands about 6'3" tall, who shoots a .32 CVA rifle he originally bought for his youngest daughter to shoot, at club matches. He loads about 20 grains of powder behind that 62 grain RB, and wins most of the shooting matches against shooters who insist on competing with him shooting their .50, .54, and .58 caliber rifles, shooting hunting load.
I have noticed, and heard some grumbling about how little powder he used during a match, compared to what others use, and the fact that the little gun doesn't recoil at all compared to what they are shooting. Sometimes discovering the " Truth" all by yourself is the best education you will get. I haven't suggested to these guys that the .50 caliber guns will shoot very accurately with 27 grains of 3Fg, or that the .54 Caliber guns will shoot well with 35 grains of 3Fg, or that the .58 will shoot well with only 40 grains of 3Fg powder. If they think shooting a 25 yard target requires them to load 90 grains of 3Fg in that .58, well, who am I to argue with their " expertise?"
All I want is a chance to shoot in a " money " match with these guys. I can use the extra loot! :grin: