R2DA's Weapons can technically be placed into tiers. However, due to the game not simply only being dependent on factors such as damage, certain weapons in higher tiers than others may still be worse than certain weapons in lower tiers. Thus, you must take this so-called "hierarchy" with a grain of salt.
Use your own experiences within the game, influences such as maps and the server's playerbase, and personal preference to determine which weapons truly are superior to others.
All of the melees, the Flamethrower, the Toybow, all removed weapons, the M202, the RPG, the X-Mas Launcher, and the FATAL5 are not included within this list. There are many reasons for not including them — a single, simplified one is that it's too hard to rank them one above the other.
These are firearms that can only fire one bullet per click. All secondary weapons are semi-automatic.
These are firearms capable of firing projectiles one after the other as long as the left mouse is held down.
Normally, these weapons are quite inaccurate.
These are firearms capable of firing a burst of bullets at a time. Usually, three bullets are seen in a burst.
Every click sends off a burst, and accuracy is quickly diminished.
These are firearms that fire one shell at a time. Every shell splits up into pellets, and every single one does their own damage. If all the pellets land on a target, it usually deals massive damage.
Usually, shotguns are also pump-action, but the DB Shotgun is an exception.
These are precision rifles that usually deal a high amount of damage.
Most snipers are also bolt-action, but the Dragunov is an exception.
These are automatic weapons, but with extremely high ammo.
With greater power, you have slowed walkspeed, pitiful accuracy, and longer reloads.