. I believe that a 165 gr. bullet or maybe slightly heavier would be able to do this. ( per #1 post )

Actually the 158gr plated RN is the largest bullet that fits in the 9mm case with a maximum seating of .300", if used.

Some 165gr bullets are .733" in length and need 1.185" OAL for safe case pressures.
Plus I don't see where the little 9mm case would gain that much with the added 10grs of weight.

Then there is getting the lead soft enough and the jacket thin enough to expand at 850fps out of a 4" barrel or less.

I am waiting to see how the 158gr Fiocchi does, if used enough or put to the gel test and posted on youtube.