That's a bother! 7.62x54r heavy ball is boat tailed as well, Hmmm....

7.7 Japaneseicon probably is not too common either. How about 7.65 Belgian/Argentineicon? Not too likely, I should think. Not many other choices.

It's a problem, esp. trying to duplicate the long OAL of the original bullet w/ the lightweight filler material up front.