So, having issues with these rigid bodies and no matter what I do i can’t get them to stop being so jittery or explode when they touch each other. Here’s a video of what is happening. i’ve applied the scale to all objects. Set origin to center of mass (volume), played around with the steps per second. Not sure where i’m going wrong here… https://youtu.be/Mr8_u7eBw9Y
I’ve tried scaling everything up as well and the problems haven’t gone away… 
Looks to me the meshes are rather complex, which might make the collision detection glitch. Maybe you can try using proxy meshes for the sim?