Identification please

[toolong]

I have this shell case
Length 47,5 cm
weigth 5,3 kg
Thickness of the case 1,6mm
diameter 147 mm (with rim, about 5 mm)
diameter without rim about 137 at rim level
Diameter at the top level about 127 (measured before widening of the case)
I found no markings at all
There seems to be a steel or iron cup at the bottom

Does anybody have any suggestion to correct the widening of this case and what would be the best process to stop the rust.

Thanks

 

[Hoeksel]

It is a modern case (based on primer) and the dimension of the rim makes me think it is a cut-down 105x607R147 case. It is ued in many guns, by many countries.