Swaged bullets are formed under pressure from lead wire. The wire doesn't have to be pure lead and can contain 3% or so antimony. In the 1970s, Speer offered cast bullets and had them with loads in their manuals. But that changed in the middle 1970s to swaged bullets which made the data drop to 1000 fps or less to allow for the softer bullet and keep leading to a minimum.
Home swaging used to be practiced, with C&H making many dies for bullets using an O frame press
CH4D :: 101 Bullet Swaging Dies. Corbin also makes swaging equipment.
Corbin Home Page Most home swaged bullets are half jacket at the minimum, but many are made with fully jacketed designs.
Casting is cheaper in the long run and doesn't depend on wire or jacket material from outside sources.