There were several variations of the Centaure produced. Among other things, provisions for a shoulder stock, consisting of cuts in the recoil shield, frame mounting screws and cutouts on the base of the grip frame, were mixed in without reason. My particular gun has the recoil shield cutouts but no frame mounting screws and no grip frame cutout. Other guns had other combinations.
The serial number appears in 7 places, and 6 of them match on my gun; the anomaly is on the wooden grips, which is pretty common. It may even be that the number on the grip is not a gun serial number at all, but rather an assembly number.
I have not shot the gun yet. I just finished correcting a timing problem in which the bolt failed to fully engage the cylinder stop notches - it would not fully extend past the frame cutout. The problem was excessive friction that the trigger/bolt spring could not overcome. It only became apparent when I cleaned the crud out of the action parts. I corrected it by stoning the sides of the bolt where it contacted the frame. The same polishing was required on the hand/spring assembly.