That's my target speed range for the 357 Maximum. Based on my tests so far I'm guessing they need 1800fps for expansion. 1693fps didn't get much, if any, expansion.
Again, I'm guessing, but I can't imagine the Speer 220 expanding at much less than 2000fps. I have shot them from my 22" 35 Rem bolt gun at 2250fps and they only expanded to .45 - .47" diameter and they only lost 15-20gr of bullet weight.
I drilled HPs into the Speer 220 based on those results and the expanded width was the same but the bullets lost 50-60gr.
