.....yes, its the russian 7.62x54R cartridge, I rebarrelled an action I bought with a british SMLE barrel ( same bore/calibre as the Russian ) and modified everything to suit. The rupture was caused by poor quality, steel cased, factory sporting ammunition. Standard 98 extractors are different, the Siamese were made in Japan.
Thanks for the info, I'll try the above places and see if they have any extractors.
Roger