Black Ops 3 has a host of weapons, ranging from general purpose assault rifles to powerful bolt-action sniper rifles, which can be customized and fitted with up to four attachments. Like its predecessor, BO3 features the Pick 10 system that gives you total freedom to completely customize your class as you see fit.
You can choose one primary and secondary weapon, and each can be fitted with one optic and several attachments. Extra attachment slots for guns can be unlocked with Wildcards. You can also carry one lethal and two tactical equipment, with extra slots unlockable via Wildcards.
Weapons in the game are unlocked in two stages. First you will need to reach a specific rank and after that you can spend your Unlock Tokens on the weapon of your choosing. Each weapon also has its own level and can be ranked up to unlock new optics and attachments.
Choosing the correct weapon for the job at hand plays a major role in doing well in multiplayer. Your aim and reaction time can be top notch, but selecting the proper weaponry gives you an edge before the first round is fired.
Trying to use an SMG to defend an area from long-range attackers won't work. While taking a sniper rifle into a map with a lot of close quarters combat won't do you any favors.