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The rifle and bullet have zero momentum and zero kinetic energy to start with. When the trigger is pulled, the bullet gains some momentum in the forward direction, but this is canceled by the rifle's backward momentum, so the total momentum is still zero.

Thanks for proving my point, because if two objects of different mass have the same momentum, the smaller object will have more kinetic energy...
That's just how it is....
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Momentum and kinetic energy are BOTH measures of energy.

And no it really isn't... The models for conservation of energy and conservation of momentum are different, but are often used in conjunction to represent a constitutive equation for motion, thus can both be used to represent the same thing. In other words, momentum can be a
representation of energy, but it doesn't mean that it
is energy...