JSP for the MP7 has more pen, higher velocity, and a much better ballistic coefficient compared to ap 6.3. I think at LL3 and LL4 MP7 is super meta. It's only 30-35k on flea for the black one.
I'm having so much success using a MP7A1/2 with only front sight no attachments, using 4.6x30mm JSP SX it mealts heads, almost no recoil and super cheap.