Guns with moving parts

I have a question on how i should approach this. I am trying to make a gun model. As we know, guns have moving parts that are visible from the outside when shooting, such as the slide of the gun. Should i make separate models for each moving part? Im new to modeling, i usually do 2D projects. Thanks for viewing.

Yeah , your model should have separate objects which move and the other parts which stay static can be combined.But make sure to that all parts which may move should not be combined to any other static parts.Hope this may help you at very basic level