USBC issues final adjusted bowling ball hardness specification Terry Bigham June 8, 2020 ARLINGTON, Texas – The United States Bowling Congress issued final specification changes for bowling ball hardness after reviewing comments from manufacturers. In April, USBC announced a proposal to raise minimum hardness to 73D for all models and to eliminate the use of field tests to check bowling ball hardness because of challenges related to workability, temperature control and variances in testing devices. The changes now are final. Based upon comments from manufacturers, USBC will extend the implementation timeline. Manufacturers will be granted ball approval at the current 72D limit through Dec. 31, 2020 and will be required to discontinue additional production of models previously approved below 73D by July 31, 2022.Visit BOWL.com/EquipAndSpecs for the 2020 Hardness Research Report and related research.