Purdey used Krupp steel from July 1898 till December 1898 for a total of 80 plus examples due to a strike I believe it was. Rigby used a Krupp absorbed concern(Annener Gußstahlwerk/Annen Steel Company) as a tube steel source. After say the mid 1880s, and for sure by 1890, there probably wasn't a dime's difference between Whitworth, Krupp & Wittner steel tubes. Only way to say for certain would be to lop off a few inches and send them thru the Dr. Hause gun-barrel testing protocol.

Kind Regards,

Raimey
rse