We've got already threads for Wien and Sofia museums, here is Lesany.
Unlike Sofia, Belgrade or Bucharest, I have proper identifications for almost everything here, but I still have a question or two, plus a large amount of pictures to share.
Let's start with the first mystery piece. So far I called it "Field gun on Ivanov mount":
Final two pictures covering very interesting pieces:
107 mm gun M1910
Regarding this, I report Ilya's feedback:
This is not M1910 produced by Putilov Plant, but 4.2-inch (106.7 mm) modification of 10.5 cm Type 38 Japanese gun that were ordered by Russia in Japan during the WWI and designated there "42-line Japanese gun model of 1905". This specimen was captured by Czechoslovak legion during the Civil War in Russia. Another one is stored on the backyard of the Military-historical Museum of Artillery, Engineer and Signal Corps in St. Petersburg.
It's more interesting than that - the Japanese 10cm Type 38 was a modification of a Krupp 10cm export gun. The Russians evaluated the 10cm Krupp gun
before WW1 and chose the 107mm Schneider M1910 gun licence built by Putilov. Putilov's production of the 107mm gun was very slow to start in WW1 so the Russians
ordered 120 modified Japanese Type 38 guns as the 107mm M1905.