Is there a trick to getting the Voltaic Stun Sweeper to 21?

[DTD_Hiro]

I just spent 4 hours trying to level the boomerang to 21 but I can't get anywhere close, my best was 9.
First off, it's not a starter weapon so you miss out on a ton of upgrade possibilities
Then it does not give you the option to choose it as a second weapon about 75% of the time (instant restart)
If you don't get it as a 2nd weapon it is not possible to level it to 21 as a 3rd.
If you should be so lucky as to actually get it as a 2nd weapon you almost never get upgrade options for it and they are only grey or green, never higher.

Is there a method or is it just RNG?

[Ninefinger]

RNG, get it early and reroll upgrades when you can to try get ones that apply to it even if they suck.

[Grim Revan]

Also don't pass up the "cosmetic" upgrades that gives extra levels without bonus stats. I'm trying to get fire grenades to 25. I was at 22 last run.

[MadConsular]

Paints jobs

[Xnian]

It's mostly luck. I'll throw this out there in case you're thick like me. I didn't realize you could reroll weapon choices until like 25 hours in...

[Perplex]

As others have said, it is all about luck and what choices you get.
Do not leave a level too fast. Do not kill the boss with the drop pod unless you do it last second before you are being overrun.

[Catteus Of Mars]

Forget about trying to beat the level on the same run... just reroll all your gold into cosmetic upgrades its how i got it done.

[Millimidget]

Recon scout or strong-armed driller, pick up the stun sweeper second, profit.

The scout has light and electrical synergies to play off of, the driller has the thrown weapon synergy, but notably the stun sweeper is not an explosive type weapon. Your ability to leverage these depends on how many/which weapons you have unlocked.

Pick up the Disposable Tech overclock at 18; it's better than One-Handed.

Save gold for rerolls, primarily in the shop, and try to invest nitra only into the stun sweeper.

Salvage the balanced overclocks at 6 and 12; this will net you an extra one level per salvage guaranteed, and there's a 1-in-3 chance with each salvage that you get an epic paint job for +3 levels instead of +1 level.