Is there a quicker way of Grind Sledge's Shotgun?

Is there a quicker way of Grind Sledge’s Shotgun rather than killing Smash-Head

I think that the only other boss that have a chance to drop it is Hyperius… Better farming Smash-Head XD, it shoudn’t take long with the increased drop rate. An other options are loot midgets but too much random

You could get it as a world drop as well or from the loot train but if you really want it, Smash Head is the best option…

Loot Midgets?