Otto:

At that weight and marked as it is, I wouldn't be surprised if it's full nitro. If you haven't already, I'd ask J. J. about this gun. He's French, studied gunmaking in Liege, and practiced his trade with Marcel Thys. I can't think of anyone in the US who would be more familiar with that type.

As for the X bullet, don't. I helped ruin a nice DR with them. They'll do nothing that a correct bullet won't and aren't worth the risk.

There are quite a few of these Belgian guild DRs with no name on them. Many are of excellent quality.