Someone mentioned that the S1-100 should be 7.63 Mauser. Wikipedia would seem to agree. " The guns sold to South America, China and Japan were in 7.63x25 Mauser calibre."
Now, this is important, because the muzzle energy of the 8x22mm Nambu cartridge (again, according to wikipedia) is 382 J while the 7.65 Parabellum has 412 J. Now, the Nambu cartridge is slightly heavier (very slightly), but based on muzzle energy, even IF Wikipedia is incorrect and the MP34s Japan bought were in 7.65 Parabellum; it should be more powerful than the Type 100 SMG.
That out of the way; the muzzle energy of the 7.63 Mauser cartridge is 545 J. Significantly higher than both.
Also; I question why any of the MP34s are in BR1; they were probably one of the better MP28 derivatives from what I’ve read.