This is a difficult challenge. It's just a bad weapon on its own since you need to run away and turn around a lot. It was one of the final achievements I went for and it took many tries. I ended up beating it with the following:
Class:
Weapon Specialist. Juggernaut would probably be possible. Heavy Gunner might be possible, but the slow movement speed is bad.
Overclocks:
High caliber rounds (damage+piercing is great; lower fire rate is barely noticeable)
The Favorite (huge damage and fire rate buffs)
And anything else that focuses on offense is good. Just don't pick the one that boosts your armor.
Tips:
Focus on luck, damage, and then reload speed upgrades. Prioritize luck less and less as you level up. It's probably not worth taking at all after level 35 or so.
Don't kill the bosses in the first two stages until you've mined as much as you can.
Some people on reddit suggested using a controller to be able to turn around faster, but this didn't make a difference in my experience. I beat it using keyboard.
Artifacts:
Anything that increases damage or health is good. Pills for improved healing on level-ups is surprisingly good since there isn't much healing during the boss fight.
Gear:
Luck is great. If you're really having trouble, just do the first stage repeatedly until you get a few legendary upgrades. My stats at the very start of stage 1 were:
280 max hp
13 life regen
93 armor
23% move speed
62% damage
31% fire rate
12% reload speed
22% crit
186% crit damage
55% pickup radius
32% xp gain
32 luck
32% mining speed
and after using the shop at the end of stage 2:
341 max hp
13 life regen
107 armor
34% move speed
130% damage
41% fire rate
12% reload speed
67% crit
186% crit damage
55% pickup radius
32% xp gain
57 luck
32% mining speed
This made my weapon upgrades:
945% damage
504% fire rate
400% piercing (very useful for the masses of enemies in the boss fight)
319% reload
Good luck