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I have seen shots go through 36h 26" wheels and I have shot through them too. Running a disc on it? Kinda negates the lightweight build in the first place.

Bullshit.

is the angular velocity
is the moment of inertia around the axis of rotation
is the kinetic energy

For I, refer to this:

which is the form by which you calculate the total moment for a body, based on the basic I = mr² formula.

Non disc vs disc:

Treating rims as if all the weight was at the eyelet, and abstact a 160mm two-piece rotor to a single point at 60mm radius rather than calculating the distribution...

XC717 disc is 25g lighter than non-disc, eyelets at 270mm
RT86 rotor 115g at 100mm

disc inertia penalty = (115 x 60 x 60) - (25 x 270 x 270)= 414000 - 1822500 = -1408500 g.mm^2

So the braking surface has 4.5 times the moment of intertia of the rotor.