Does anyone know where or how Beitzinger marks his builds? A friend has a custom rifle on a Champlin action that was purportedly built by him, and I'm trying to help him confirm it.

Depends. During a period when "marking" meant you were the manufacturer, I think, he didn't mark everything. I'll ask him. I think he had some marked in script also

Here's mine.

Rich, thanks. I wonder if he might remember the build?