Buckstix,
You are probably aware of this, but John Buhmiller developed the cartridge now known as the .500 A-Square, along with the cartridge later christened the .460 Weatherby. Both are the .378 Weatherby necked up to .510" and .458" respectively. John and I came up with the same idea at roughly the same time, which was my .505 SRE, made by shortening the Weatherby case to 2.5" and necking up to accommodate a .505" bullet.