Peter:
I'm pretty sure it was used at least till 1972. I know that it was recognized in 1963 by the Brits. But I usually can't get the closing date of the Weipert facility correct, but I think it was 1954. Then the facility was transferred to Brno. Without the star, the proofing effort would have been in Prague. It may very well be that the Austro-Hungarian were the only ones to put the weight of the tubeset on the lower rib.

Kind Regards,

Raimey
rse