I recall seeing some "Old Info" where they measured the pull necessary to open a crimp. There needed to be enough that the crimp would not open on firing the other barrel, but not so much as to raise pressure unduly. I have never seen a comparative measurement between crimp strength & a tight fitting overshot wad in a ML'er. The tight wad was necessary in the ML'er to prevent the charge from moving forward when firing the other barrel. I seriously doubt there is that much differences in the tight wad & opening a proper crimp in a paper shell though.
