Make it so you need to sprint x amount of time to get full slide distance, it would nerf shotguners without needing to kill shotguns. If you just spam it like an ape you stop going anywhere. They would actually have think about it like you can click sprint and instantly go full distance silly.
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Or just stop letting players get that close that they can not slide into shotgun one hit range. The games time to kill is more than short enough to stop people getting too close to you so either you are closing the distance to them all the time or letting them get too close.