New Model Double-Action Belt Revolver

[Kerry Kenady]

Some double-action belt models have a metal insert through the right side of the frame. What is its purpose? Why do only some revolvers have this feature? The mainspring on the belt model recently acquired seems weak. Is this a common problem on these revolvers? I'm not familiar with the internal workings for this model. Is there a reference showing the internal parts and how they are assembled?