Warning

This is meant for as an intermediate weapon mentioned in my beginner Volt guide, and maybe mentioned in my intermediate [Rhino] guide if I ever write one, so no Orokin Reactor or Forma.

Acquisition

First of all, the blueprint. Unlike most weapons in the game, the main blueprint is actually a random drop. You will have to kill Drekar Troopers (those blue grineers) at MR2 and up in order for a slim chance to get one. So we are doing Exterminate missions that spawn those troopers (Grineer Sealab Tileset). The first and best one to start with will be the Earth, Mariana.

Next, the materials. Most materials required in the blueprint should have been collected at some point during game play except one, the Plastids. This is why I suggested you to halt the acquisition of this gun till AFTER you have went to Phobos, cause that's the quickest way for us to get them. The best farm will be Phobos, Stickney. Just go there, do 5 minute of survival while running around looking for the deposits.

Third of all, the mods. If you are coming in from my beginner shotgun guide, then skip the ones below. Otherwise, here's where you can get them.
1. For Hell's Chamber, it can be obtained by doing T1 (Level 1~17) Defence for 15 waves to get Rotation B for a 8.33% chance.
2. For Point Blank, it can be obtained by doing T1 (Level 5~15) Bounties on Cetus, Earth till Stage 2 for 7.52% chance and Stage 3 for 30%. Both stages have a chance to drop those mods.
3. For Chilling Reload, you will need to do Nightmare Mode Missions (beside Rescue) on either Mercury, Venus, Earth, or Mars. Of course, you will first need to clear EVERY NODE on that planet in order to gain access to those missions.

Last but not least, Credits. For some reason, this site never shows you the credit needed to level up your mods. So here is a quick run down. As you can see from the chart below, it cost over 85k credits to upgrade everything. So how the heck are we supposed to get that? Welp, the best in level credit farm is actually on Gabii, Ceres. Just by simply completing this survival mission gives 20k+ credits, the main point here is: COMPLETION. That's right, by simply completing this mission, you got 20k+ credits. And all it cost is 5 minutes. Also, the more player in your group, the more it pays, so make sure you set it on public.

And finally, Endo. You see that ball looking thing below the build name? That's right, that's endo. You WILL need it to upgrade your mods. The quick and simple way to do it is just do T1 Excavation and leave after 2 drills (every drill on rotation A has a 42.9% chance to get 100 endo) which cost around 6 minutes if lucky. So just rinse and repeat that at least 8 more times. Of course, then there are the Ayatan Treasures. Through out missions, you have a 1/7 chance to get a sculpture spawn. So find them and fill them with stars, which have a random drop chance from storage containers and lockers (keep an eye out on either that white icon, and mark it for your group using "G" if not playing solo before picking it up). Ones completed, you can exchange them at Maroo at her Bazaar on Mars from 1,425 endo all the way to 2,700 endo.

Next Step

Grab [Hek]'s Blueprint from the marketplace for 15k credits once you [Reach] MR4. There is just nothing better at the level.