I have no available MkVII balls and don't know where to looking for them. I reload Sierra and Hornady, sometimes available PRVI PARTIZAN but i find them less consistent . So handloading is a way to control barrel vibrations .. Jay Seets wrote that a gentlemen, Mr. F.G. Price experimentally located nodes and antinodes of a No.1 MkIII with heavy barrel. He found, following Jay Seets book, 8 nodes and 7 antinodes. Last but not least Sweet says that accurate location of those point tell us the location of packing.. It would be very interesting if we found "the experiment" Mr. Price used to locate nodes...