I have the following two 9mm AP bullets in fired condition
While the two bullets externally look identical, one bullet is 5.3 grams while the other bullet is 7 grams.
The 5.3 grams point to a 7N21. The 7 grams point to an SP10 but the location of the red sealant ring is at the same position.
From what I understand, in the 9x21 cartridge, the bullets protrude from the case mouth more than a millimetre more than in the 9x19mm rounds.
The question is whether there is a heavier version of 9x19 7N21 that uses the SP10 bullet but seated deeper to satisfy the maximum oal length