8 X 63.5 GECADO

    

Case length is too short for it to be a 8x65R Vierordt (EXP21)

Measurements:

Bullet:   8.01mm
Mouth:  8.76mm
Neck Dia:  8.82mm
Shoulder Dia: 10.00mm
Base:   11.00mm
Rim:   12.33mm
Neck length:  9.87mm
Case Length:  63.53mm

This case also resembles the Roth 8.2x63R (EXP56)