Looked at the 7 irons for both and estimate the PTM BBGM to be around .900″ and the MAX to be approximately .760″. Tolerances allow for some variation from club # to club #, but should not be much. The difference between the PTM and the MAX seems like a little more than you would expect, but the PTM was a pretty big head and Max has a shorter hosel and lower heel height, different toe to heel radius. Anyway, that is the rough estimate. Hope that helps. Probably going to need to pull one and and dry fit install one and just see what the exact difference is going to be.