I'm trying to convert "unknown" CRS of the shp to the WGS84 UTM zone N34. I've tried to do it with saving of shp in different CRS (Save as) but I did not succeeded. I've checked the situation with open layers and using of on-the-fly transformation and matching is far from perfect (500-600 m difference).
Unknown CRS has been showed in QGIS as USER 100001 with the following parameters: * Generated CRS (+proj=tmerc +lat_0=0 +lon_0=21 +k=0.9999 +x_0=7500000 +y_0=0 +ellps=bessel +units=m +no_defs)
It should be a Gaus Kruger projection (Bessel 1841) for Serbia. I've tried also with changing of shp and open layer to MGI 1901/Balkans zone 7 and MGI/3-degree Gauss zone 7 but the situation is the same.
Note: Shapefiles should be very precise as they were obtained by the Public Enterprise. Unfortunately, they're not interest in delivery of the shapefile in a different CRS.
I would be very greatful if someone could help me regarding this issue.