Abstract: A bowling ball is made with a shell and a core of different compositions, with the core having a greater density than the shell so that the finished ball will have a predetermined weight; and the core also having a maximum dimension along an axis passing through the top of the ball where the finger holes are to be drilled, and a minimum rotational inertia around the same axis. The core is temporarily supported on a pin while the shell is cast around it, and the hole left by the pin is filled with a material of distinctive appearance to designate the top where finger holes should be drilled.

Abstract: A bowling ball has a surface made from a material containing a minor quantity of functionally terminated liquid elastomer combined with a major quantity of resin-forming material reactive with the functional end groups of the elastomer, and has a greatly enhanced coefficient of friction against ordinary bowling lane surfaces, permitting superior control of the path of the ball and therefore better scores by the bowler. Such surface compositions are preferably made from a liquid polyester resin of the type which is hardenable by a peroxide, with addition of a liquid vinyl-terminated diene polymer or copolymer in a quantity amounting to about 10% to 35% of the mixture.