Silver, You're supposed to downtune those strings right?? Then it's not supposed to snap.
But who's buying? lol

You're looking at the wrong place.
There are a few factors that can be contributed from the extra mass of jumbo frets towards the length of the string vibration. (Whether you take it as a simple harmonic motion or you want to purely look at it as a wave function)
Such as elastic potential energy or you can derive an equation from Newtons Second Law.
For elastic potential energy you the k constant is equivalent to mω^2.
For Newtons Second Law you assume tetha, the angle of the amplitude from the equilibrium position(it forms a small circle) as a small angle and delta m = µ delta L where µ is the strings linear density.
Then apply F = ma because at the moment of amplitude of the string, where the delta is taken it has a centripetal acceleration to the center which is at its equilibrium position.