The 20gr peter out fast because the BC is quite low, maybe by 400Y??? and they will blow in the wind a lot??
25gr will do a little better. I've seen pics of guys hitting steel at 500Y with the Vmax but it was an improved 17R version.
I used the Kindler 30gr Golds with .28BC in my 9 twist and those actually are quite impressive at 550Y, we shot them at 675Y but it was hard to spot hits on the steel.