U don' t say if your ml can safely fire the magnum powder load or not. If it can,
150gr of powder, pushing 4 example 240gr hollow-point (sabot) out to 200yds is not a problem if U can hit what U aim at. If not a magnum, 100gr of powder with 240gr bullet will kill a deer out to 120-150yds no problem. I use pyrodex pellets.
For sighting in your rifle check out www.chuckhawks.com