How do you determine if an AK trunnion is cast?

[Giggles]

How do you determine if an AK trunnion is cast if the rifle is already built?

[Bret]

It's kind of hard to describe. I'd start by looking for a seam and look at the surface. See this pictures in the link below. Can you post several close up pictures and provide all the information on the build that you know?
http://www.akoperatorsunionlocal4774...unnions-drama/

Here's a good video explaining the differences.
https://www.youtube.com/watch?v=i03Kic5gaRs