To score one of Destiny 2โs most powerful and exotic weapons, youโll need to do a lot of grinding. We know what youโre thinking, and yes, itโs hard to believe that youโll have to do the same thing 200 times in Destiny 2 and just hope the RNG gods smile on you eventually. /s
The Jotunn rifle is hard to get, but itโs worth the effort, especially for players who spend a lot of time in the Crucible. It fires powerful homing bolts that can devastate opponents in the PvP arena, and itโs an excellent weapon in most PvE encounters as well.
The process of acquiring this awesome gun isnโt as convoluted as some others are, but it is heavily dependent on luck and patience, so make some popcorn, grab several bottles of water, and get comfortable before committing to the task.
Step 1: Unlocking the Four Forges
The first thing youโll need to do is ensure that youโve completed all of the Black Armory missions for the Izanami, Gofannon, and Volundr forges.

Once those three sets of missions are done, youโll want to jet over to the Tower Annex and talk with Ada-1, the Black Armory merchant.
Step 2: Completing the Weekly Bounties
Ada-1 should have two weekly bounties available (provided you havenโt already done them this week). One requires you to complete a number of daily bounties and the other revolves around activating forges. Accept and complete both missions to earn Black Armory Schematics, which you can then trade back to Ada-1 for Powerful frames.

Youโll need several Powerful frames to get the Jotunn rifle (possibly as many as โa whole bunchโ if your luck is bad), so thereโs no such thing as having too many.
Step 3: Calibrating a Truckload of Powerful Frames
Pick one of the gold Powerful frames in your inventory and calibrate it by following the semi-random instructions on it. If you have more than one frame on hand, you might as well calibrate them all while youโre out running aroundโdoing so will save you some travel time in the fairly likely event that you donโt get the Jotunn rifle on your first try.

Once all of your Powerful frames are calibrated, head back to Ada-1 to finalize the process. When thatโs done, your new forge-ready frame will tell you to use it at one of the first three Black Armory forges, either Gofannon, Volundr, or Izanami.
DO NOT FOLLOW THESE INSTRUCTIONS.
Step 4: Pray to the Bergusia Forge RNG Gods
Ignore what the frameโs descriptions tell you and go to the Bergusia forge, in the southern area of the European Dead Zone. Use your completed Powerful frames there and you might get the Jotunn rifle in addition to whatever weapon the frame blueprint is for. The Jotunn rifleโs exact drop chance is unknown. It might even vary according to certain conditions that are also unknown.

As is usually the case with anecdotal reports gathered from players, itโs impossible to do much more than guess. Some people claim to get another Jotunn rifle every week, while others have been trying for one for months on end without success. Of course, there are guesstimates everywhere in between, too.
We wish we could tell you that thereโs something you can do to improve your chances, but youโll just have to hope you get lucky. If you donโt get the Jotunn rifle after your first try, keep going back to Ada-1 for Powerful frames every week and trying again. Stick with it and sooner or later youโre bound to get what you want.
While waiting for the rare drop, you might want to explore some other exciting FPS games or games like Destiny.