I think the higher the grade number, the higher the grade/quality. Your gun looks nothing like my Grade 6 Manufrance Ideal. My grade 6 has a "solid" action body (no bbl. lumps come thru the bottom) and also has a completely different engraving pattern. Does your gun have a number indicating its grade stamped/engraved anywhere on the action?
You have a very nice example of a Manufrace Ideal by the way. I like your guns engraving pattern, fits the gun well.

Dustin