This is my Polish Wz.91/98/26 Mosin Nagant M91 conversion to 8mm Mauser. It is made by Machine and Weapons Factory "ARMA" in Lwow (now Lviv in Ukraine).

My particular example does not have a manufacturer marking, but it can be assumed that it was converted by ARMA. The Warsaw arsenal doing the same conversions have large Polish eagle on receiver and letters W.R.N.1 stamped. Unfortunately, a year is not stamped on ARMA conversions, so a date cannot be pinpointed.

What is really nice is that everything but the bolt matches, but the bolt is correct Polish one. The receiver has a circle proof on the recpoeiver, which is an unknown/unverified marking. Per a Polish study done by Piotr J. Bochynski, it is assumed it is some sort of high-pressure firing procedure acceptance marking.

The interesting thing about this example is that it wasn't refurbished during the 1930's like many of these typically were, which explains why it still has Russian sling slots in the stock. Those refurbished in the 1930's have those slots plugged and Mauser type swivels installed to accommodate standard Polish issue Mauser sling. In these cases, the stock would have had a marking of "ZBR.2" or "Z.W." followed by a date of refurbishment. Refurbished rifles have been marked as early as 1934 and as late as 1939. This stock just has a Z in an octagon, which is just an unknown factory acceptance proof mark.