For the French: the shortened rim-less 8mm. The AP bullet from the Lebel round might be a good start, since it was a lot lighter than the "balle D" (9.6g vs. 12.8g). Instead of the 3.2g for the Lebel AP loading, perhaps use ~2g, that is still twice as much as in the .351 WSL. Make the MAC 24/29...