Interesting thread.

I seem to remember reading that the british military used 375's during WW1. They were given to snipers to defeat the steel plates german snipers would use to protect themselves. The 375's came from several different makers and were iether biught by the Military or privately. That is if I remember the article correctly.

As for NZ rifles having the British proof marks it is possible that a NZ company bought them from surplus stocks or the NZ govt might of required all firearms comming into NZ from Europe to be proof tested in Great Britian. This is just speculation on my part.