I would just like to know how the weapon modification works ??

You go to a town talk to a gunsmith, they will upgrade your weapon for a fee, they make upgrades like bigger clip, reloads faster. I'm not sure but I think you can find pieces of upgrades in the wastes too

yeah, think I heard you could find them, I assume you either use a workbench or get a discount at the gunsmith for providing the parts.

thanks guys ! can't wait for this game !