Speed of sound is only around 340m/s, or 1,150 fps. Pretty much any .22lr will do that. The media you are looking at might have a great variation in malleability depending on temperature. Something to consider in November.
As far as providing a convex surface, look at our Earth's surface. We are talking a big scale. Surfaces are effectively flat to meteor impact. Local topography has a far greater effect than the curvature of a spherical surface.