I was under the impression that different bullets with different base types and/or more mass in front of the ogive would have different free space at same seating depth. Wouldn't that effect tuning and max charge?
The bullet shape will affect a number of different things, but max charge weight really isn't one of them to any meaningful degree. Where they are seated matters (e.g. jammed or jumped), but you should be setting each bullet type differently regardless - will be based on your measurements.