Errm, if the Rigby rising bite classifies as a "dolls head" then I think we can take it as a given that it adds strength as it is universally recognised in the trade as the strongest double rifle joint but was so expensive to produce it was abandoned. The Westley Richards dolls head is a masterpiece too, just my opinion (I´m not saying you need them, just that they are tough. I actually don´t like them on dangerous game doubles as I think they might slow down reloading but if you ever get the chance to see a Rigby rising bite in function it is a wonder smile ) best