.475 Linbaugh was first formed from .45-70 Govt. cases. Though the factory offerings have thicker brass, and slightly smaller rims. .500 Linbagh was formed from a Remington case of some sort. When Remington stopped making brass for that John came up with .475 Linbaugh from .45-70 knowing the cases would be around for a long time to come.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.