If this is a dead horse, I don't mean to beat it, but after seeing that a GP100 or S&W L frame holster might work for Nagants, I had to try it in an old leather holster I had lying around which looks like it would fit an L Frame. Seems to work like a charm. Not fashionable, but would do well for farm work. If you google images for B07-44SF and/or the nomenclature 1095-00-480-6807, you will see the holster. Here's a pic of my nagant in the holster:
