How to split obj model into parts?

Question

3D

There is a 3d model of a pistol.

You need to break it into pieces, the way it was once assembled by someone. Tell me, please, what needs to be done. I downloaded Blender.
The file itself - https://yadi.sk/d/f5Eb4X8DkibMuA

Answer 1

You need to break it into pieces, the way it was once assembled by someone.

has a lot in common with "change the operation of the program without having the source code" (after all, which of them compiled it).
Not that it's impossible. But it's a little more difficult than it might seem.
obj - a file is just a set of polygon coordinates. There is no information about the components of the product in it.
For your task, kmk is optimal to import it into some kind of cad (solidworks, for example) and actually design it from scratch , tracing the outer contours.
CAD is more suited to all sorts of mechanical engineering stuff (like shutter movement) than a 3d editor.

Answer 2

And why did you get the idea that this model contains all these internal parts that you want to disassemble it into?
There can be a maximum of 3-4 parts that should move during animation (body, trigger, bolt, striker), and there are most likely no internal springs, and other parts in this model, so the "disassembly" process is impossible, and it's easier to find drawings and on them to model all this.