Blanks take many years—up to 10—to cure, dry, and stabilize in air. Kiln drying cuts the time to under a year, but can crack some types of walnut. In the 1960s, Browning found a source of walnut in California and, not having enough time to kiln dry it, tried a new method of drying developed by Morton Salt for the furniture industry. According to firearms historian Ned Schwing, Browning filled a room the size of a football field with 5x5x8-foot stacks of blanks which were then covered with salt. It worked—except for the part where the moisture pulled out of stocks at the top of the stacks ran down and into stocks on the bottom, essentially brining them. Once those stocks from the bottom of the pile were put onto guns, they rusted metal, often from the inside, where you couldn’t tell what was going on until you pulled the stock off. “Salt wood” Brownings were made from 1966 to 1972, with the majority of affected guns being made from ’67 to ’69.