The floating bolt head may help with offset. What about axial misalignment? If the firing pin is rigid, exactly how much can a floating bolt head help(bushing your bolt head might kill any benefit)? Looking further it only floats in one axis, perpendicular to the retaining pin. Seems to me that might help with even contact on the lugs...Then how much float can happen, Or does an modular bolt system reduce machining cost and reduce cost and inventory. Aren't we really talking about the loose tolerance in the bolt body to raceway allowing for some offset( but not of axis). Why do some rifles have a primer strike so far off center? Seems to me only the loose tolerances allow for any alignment correction. I'm not an engineer or an expert but those are my questions when I hear something like the bolt head fixes everything.

And then there is the progressive scope alignment issue with a barrel tenon that is not in the same axis as the action/scope mount screws. Floating Bolt head wont fix that either.

These are the reasons most custom action makers make everything parallel, perpendicular and concentric, even makers like Bighorn/Zermatt who claim a floating bolt head. Savages are probably accurate because of them straitening their barrels more than any other factor. Again just a layman's thoughts and beliefs.