Physically Simulated Bones

I am trying to make a strap for a weapon with that will be physically simulated, how do I do that, with each end of the strap attached to the weapon?

I linked the image below to show help.

You need a skeletal mesh with many bones, and then you create a PHAT asset with custom constraints and colliders for the simulation.

In the image you show it looks like you have the collision set to something incorrect which is causing your bones to spaz out.