I read an article on folding guns which explains their strenght by two factors:
a) the power that lifts the barrels off the action depends on the leverage between the pivot point of the barrels and the lockup element(s), the greater the distance between the pivot point and the lockup the less power, and in folding guns this distance is about three times greater than in common designs
b) the pivot assembly itself is shaped as a complte crossbolt, and it holds the barrels more firmly than the regular setup.
