Method of determining bushing size, is to measure the neck wall thickness of the cartridge cases with a ball type or tubing micrometer. Double this measurement and add the bullet diameter to calculate the neck diameter of a loaded cartridge. As above, subtract 0.001" from this figure to determine bushing size.
Hornady, RCBS, Redding, Short Action Customs and Wilson Bushing are all interchangeable.
Forster Bushing are not interchangeable with other brand.