One of the main differences between casting and swaging is the tools used to complete the task. While casting bullets requires a method of melting metals, swagging doesn’t need molten metal to create the round. This can be listed as an advantage for swagging because accident prone people may hurt themselves with sloppy pours. This also gives a point to swagging because you are much less likely to start a fire.
However, because you are filling a mold when casting bullets, you are much more likely to get the same bullet weight every time as apposed to swagging that can give you multiple bullet weights depending on how much material is added or even the types of material used. That is an advantage for casting being more consistent with regard to bullet weight.
This creates the challenge when swagging to create a number of bullets with consistent weights. Different bullet weights are obviously going to act differently when fired, even if the powder loads are identical. Heavier rounds fall faster than lighter ones and if someone makes their own ammunition for firing and wants to zero the optic that they have mounted on their firearm, they will have a difficult time using bullets that were swagged differently.
