An apparatus for forming an inward dome in the bottom wall of a metal can body having a beveled peripheral edge bordering the bottom wall. The apparatus includes a housing which supports a convex die member adapted to engage the bottom wall of the can body to form the dome. A pressure ring is disposed radially outward of the die member and is mounted for sliding movement with respect to the die member. The pressure ring is provided with a beveled surface which is adapted to be engaged by the beveled edge of the can body to prevent deformation of the bevelled edge as the dome is formed in the bottom wall. The pressure ring is connected to an air spring which provides uniform resistance to movement of the ring relative to the die member. In addition, the housing and die member are connected through a second air spring to a fixed support and after the dome has been formed, continued axial movement of the can body will result in compression of the second air spring to insure full formation of the dome.