Skeletal Mesh+Shadow Glitch in UE4

You are focusing on the wrong thing. In a tfps game you will never be able to spot the skin being uneven by your bicep.
In fact you’ll be hard pressed to even see your bicep.
In third person with movement you’ll never be close enough to spot even the original kink.

That said, you could try .005 as a cut off and see if it makes any difference.

but remember that unless you give the player the possibility to move the viewport camera around like in editor, they will literally never be able to spot this.