I have been corresponding with Jeff Cooper's daughter. Lindy, and I interviewed her last night. That interview will publish on Monday.
In an email today, I asked about the myth that injury is what led to the bent support arm (applied to Mr. Cooper). Here is what she wrote:
"He smashed his right elbow in a fall on the ice while holding my sister when she was a baby. He went through some very painful rehab and had a dent in his right arm where the elbow bone normally resides.
This had NOTHING to do with the Weaver Stance. The Weaver Stance is what Jack Weaver used and he kept winning so Dad and John Plahn analyzed why this was so and came to the conclusion that an isometric balance is achieved when the strong hand pushes outward and the weak hand pulls inward................and this push-pull effect enables a shooter to better control recoil and regain his sight picture more quickly. That is it."