It took quite a while to finally get it. I am done grinding green shotties. LOL
Edit: I actually have so much fun playing with the boomacorn, I have been thinking about creating a boomacorn build.
2nd Edit: I should have trolled the Nisha Top Gear section before recording my vid. Apparently, I can proc Hot Lead with it.
Copied/Pasted from @Chuck80 Nisha Top Gear cause I didnāt see a way to link just that specific section of the thread:
"Boomacorn59
The Boomacorn is pretty special. Itās a Jakobs shotgun that shoots 5 small ārocketsā that deal pure splash damage (so they canāt crit without Tombstoneās help) each with a random element and massively increased damage. If you can stomach the Neighing sound it makes each time you fire, itās one of the best mobbing guns out there. Almost guaranteed one-shots on normal mobs. Aim at the ground at your targetās feet (or shoot from above) to be sure to land all explosions near your targets. Note that while it has all elements at its disposal, itās officially a non-elemental gun, so it does benefit from Magnificent 6 and Hot lead.
Elements: Random
Best Parts: Punisher or Safeguard luneshine. Other parts are fixed
Obtaining:
Grinder/world drop"
Thank you @Chuck80 going through the SG section of your OP was very helpful. Iāll be digging into it cause Iād like to create a build around this SG. Itās just too much fun. 
Changed my build after learning hot lead can activate from the Boomacorn. So here is what I have moved towardsā¦Let me know what you think. Should I chose a diff com? Should I move a few points around? I appreciate the feedback. Good or bad. 

This was my choice of Com to use. I feel that the crapshooter will out DPS the Six Shooter just due to the Tombstone buff at 11/5. But with the boomacorn, trickshot doesnāt activate, so I felt different skill buffs would benefit the boomacorn a little more. I just hate wasting points. Feel free to advise if you feel differently.

Here is my skill point distribution
Edit: After testing the boomacorn with the 30% chance to bypass enemy shields which was recommended by @khimerakiller , it has now come to my attention that this is useless on the boomacorn, let alone any weapon that shoots rockets and not pellets. After Khim had pointed this out I took his advice and tested it over the weekend. Epic Fail! What a bummer. Rockets canāt bypass enemy shields apparently.
After discovering this I decided to test all the RLās I had been banking. All with the 30% chance to ignore shields. All pointlessā¦
Thanks for killing my high @khimerakiller . 
That all being said, the build holds up pretty well. When I make my way to a boss, I swap out the boomacorn with a Docās Flayer. After boss is over, I switch back and continue mobbing and neighing. LOL I think a better version of the Six Shooter would suite me well. Iād like the Mag6 or even Crack Shot at +5 instead of Quick Shot. Itās a subtle difference.