Quite recently a discussion of Lee’s table of maximum pressure for cast bullets at different Brinell hardness scores appeared here. It might help to understand where those numbers came from. The Brinell number is arrived at by pressing a ball bearing (actually something like a ball bearing) into the metal being tested using a measured force on the ball. Then, after measuring the ball and the size of the dent, the surface area of the dent is calculated. The Brinell hardness number is simply the the pressure on the metal being tested in kilograms per square millimeter or the ratio of the force over the surface area. So, a Brinell score of 10 means the metal supports 10 kilograms per square millimeter.
Us Yankees don’t use the metric system; we’re stuck with pounds and square inches. For you mathematically inclined, the conversion is quite straightforward. For the rest of us, trust me, one kilogram per square millimeter equals to 1422 pounds per square inch. So you can simply multiply the Brinell figure by 1422 and get what any bullet supports. Lee’s figures are nothing more than 90% of that number.
As others have pointed out, that information is of very limited usefulness. For example, I had a model 29-2 (they were famous for oversized throats) that would lead like crazy with straight Linotype and shot super soft bullets with no problems. The soft bullets were swelling up under pressure to fit the chamber while the Linotype bullets were suffering blowby.
Ed
Lee max pressure
Linear Mode
