The story I came up with for this was, someone once used this in battle with The Root, ran out of bullets, and in desperation, used this gun like a baseball bat and bashed surrounding enemies with it. During the fight, the stock of the gun was broken off, and the front areas where barely hanging on. That person died in the battle. Later what was left of the gun was brought back and restored as best it could be., hence the screwed in shovel, and metal supports hammered in the front. Now the user can use it to avenge the fallen. Etched in on the side shows evidence of the various owners who this weapon has protected.