Ballistics will not be the same for the scope calibrations in my opinion based upon the velosity between the two is greatly different. However, I see no problem using it for a while until you can get a replacement. As you said sight it in at 100 yds and then shoot out to 200 to see the point of impact vs the graduation dots/bars whatever the scope is set up for. You probably have at least 800 fps difference probably a bit more between the ML and 270 so the hold over marks won't be the same for the two different rifles. If sighted in at 100 yds knowing point of impact vs the actual scope yardage marks become easy after that. You may want to hold your shots to under 200 yds???