SetSynchronizedValues using velocity

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I'm moving my character and projectiles using a rigidbody and .AddForce(direction, ForceMode.Acceleration);

How do i calculate what should be passed into SetSynchronizedValues() ?

You would think that passing in rigidbody.velocity would work, but it does not, the value of rigidbody.velocity seems to be too high. Any idea how to calculate the correct value based on the rigidbody's values?