I used a meme from memegenerator. Maybe it's due to this poor complaint.
The Carbon Roller is already balanced. It's made for people who prefer to be more offensive, with a faster fire rate, thus making it a great close combat weapon and less of a "hit and run" like other rollers. This difference, of course, creates of course it's weakness, it doesn't one shot people when rolling on them, like any other roller. It's lighter, thus not heavy enough to kill. This makes the Carbon Roller less effective as a surprise weapon, since you can't surprise people by rolling on their poor faces.
If you think this weapon is OP, you don't know how to fight it. It's simple to understand. So grow up from this way of thinking, and find ways to counter those filthy rollers, if you want.
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As for myself, I don't find any weapon OP. They all have weaknesses, strengths and utility. I do feel however that some less used weapons need tiny buffs to make them more usable. Some weapons are already forgotten, let's buff them so they can compete against prefered weapons.