Yes and no.Gras was a metallic cartrige gun-Chassepot was needle gun using paper cartrige .
Number of Chassepots were converted to first model Gras (cocking piece is a good giveaway) but great majority were build new using much stronger steel alloys.
I have and shoot 8x50 Lebel 1915 conversion of Gras-awesome rifle but not as accurate as any later bolt actions I ever shot.
I hope one day Pedersolli(or someone else) makes good copy of original Chassepot with all tools,gaskets and paper cartrige making stuff.
Finding real one in "safe to shoot "condition borders on impossible at least in N.America.