[Rocco]

I'm not sure I really like a standard 3xBB here with an M of 7. You have the table big stack, who's already put 300 in, left to act. I often see these "big stacks" smooth call (or re-raise) your raise and the question is what you do if you don't hit the flop at all? If he checks you'll be tempted to throw out a continuation bet and that makes you committed. Let's say your M is 7, that means your stack is 6300. A failed raise brings you down to 4500 and a few folded hands later it's down to 3600. Not desireable at all... I'd go all-in or fold here... With an M of 9-10, a 3xBB raise is more likely from my part. On the other hand, if SB is weak-tight, I'd raise 3xBB with lower M's.