Ouch...
OK after a bit of searching found the exact model i had
http://www.ebay.com/itm/RARE-RUSSIAN...-/151064405779 - it was the 1958 version. The exterior of the barrel has a lot more lumps and bumps than yours. Also it came in a solid plywood case with 3 full aperture filters and a screw-in screwcap that added another 15 cm to it. The corrector was uncoated.
If you dismantled the corrector on yours don't be surprised if its a doublet... just be very careful not to scratch the secondary. Yep, at least 3 cm of solid glass up front, easily.