I was under the impression that velocities over 1,000 FPS in cast bullets would surely begin to lead. Please look at the reference below. Could this be the case? I am confused.
"The mid-1950s were another fertile period for the .38 SWC with the introduction of the K-framed S&W Combat Magnum and the Ruger .357 Blackhawk. Velocity was the selling feature of the cartridge and Lyman chose to capitalize on that feature, while simultaneously capturing those features that Keith and Sharpe had espoused in their designs, with the 150 grain 358477 (cataloged in 1957). With this bullet it was easy to achieve 1500+ fps from the .357 Magnum and 1000 fps from a .38 Special, and do both with superb accuracy and no leading. For my money, the original 150 grain 358477 is the finest .38 Special bullet ever designed. Loaded over 5.4 grains of Unique, it generates 982 fps from a 6” K-38 Masterpiece with exceptional accuracy.”
The BIG question: How do you get a Plain-based bullet to travel over 1,000 FPS without leading? I am especially interested in doing this with .357 Magnums at 150-180 grains and .44 Magnums at 240-250 grains.
Thanks