Upset Upset: The tendency for a bullet to become more cylindrical on firing due to inertia. Also known as slugging. The expansion on impact of a hunting bullet. See mushroom. Share this:Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window)Click to share on Pinterest (Opens in new window)Click to share on LinkedIn (Opens in new window)Click to share on Tumblr (Opens in new window)
