If you intend to use physical magazine firearms the various pieces need to be broken up into seperate skeletal meshes. I am not sure if the packs come that way or not. If they dont you will have to follow thr first tutorial to rig them correctly.
If you wish to use just the basic firearm then combined meshes with animations will work. Basic firearms dont have slide/charging handle manipulation.
We currently have 5 modern weapon packs planned (3 guns each) that will be sold seperately and work with WM with no outside setup needed.
The tut i am doing uses a chamferzone model btw, akm, and all his meshes in that ultimate pack will need to follow similar steps to work with the physical magazine firearm system in weapon master.