QQC-Mastery

This week, I was very interested in the part of the reading that talked about how some people leave West Point after the first semester, and others go on to "military mastery" The answer was grit. My question is; If you have a certian level of grit, can you still master something that could require more grit? In other words, can you still master something if you dont have enough grit? I think that true mastery can only come from genuine passion about something. Even if you work really hard, you wont be a master unless your grit matches the pain you have to go through to get there.