Thank you very much!
Hoot4570 - thanks a lot. Won't be easy for me to obtain a copy of William Goforth's book, but I'll try to get in touch with his daughter.
Daryl, thank you for your kind offer. I might write to you about it some day, when/if I start to dig into the issue of the design differences between IJ and Russian-made guns of this design. Apparently, there were some.
Mike A. - yes, sorry, I meant rolling block. Thanks for the info that copies were made in Belgium; Petrov's and his rival Evdokimov's had a lot of their guns made in Belgium, and might've easily sourced their Remington actions from there as well. Before Trans-Siberian Railroad, it would've made much more sense logistically.
JDW - the Russian Army bought numerous breechloading designs before they finally settled on Berdan #2, and the conversion of those into shotguns was a sort of a national industry. It continued when the Berdan was replaced by Mosin, and then with redundant rifles from both World Wars - in fact, the last converted shotguns were made in early 1950s.
And now a few pictures
