Fallout 4: Rare Gamma Gun aka Lorenzo's Artefact location guide

Avid Fallout fans are in for a treat as YouTuber MrBossFTW aka Ross has shared a comprehensive location guide for finding one of the rarest weapons in Fallout 4, the Gamma Gun or Lorenzo's Artefact. Unlike the regular location guides involving a four or five weapons, this one is a dedicated tutorial to find just the Gamma Gun.

As Ross admits in his latest gameplay video for Fallout 4, the entire mission involving the process of acquiring the artefact takes roughly 90 minutes of play time. The quest for finding the weapon has been basically split into four sections.

Here is how you can find one of the rarest weapons called Lorenzo's Artefact in Fallout 4:

Just find a ghoul named Edward Deegan at one of the multiple locations including the Diamond City market area, Bunker Hill, Dug out at the Colonial Taphouse or at the Third Rail Bar in Goodneighbor.
Basically, Edward will offer you a quest, which will require you to work with a scientist named Jack Cabot. Just go to Jack's house and he will ask you to complete a set of challenging missions or tasks for him.
The first mission requires you to take out a couple of raiders who stole one of his serums and return the same to the scientist. This is the easiest part of the entire quest, which will only require you to kill the raider in possession of the serum.
In the next mission, you are asked to find Jack's lost sister. You need to visit Third Rail in Goodneighbor and ask a few questions to people around the place in order to investigate the mysterious disappearance of Jack's sister. You will soon discover that she actually ran off with some guy named Brother Thomas, who is said to be a hippie or some cult leader.
After some interrogation and intimidation, Thomas will reveal the actual location where Jack's sister, Emogene, can be found. You will eventually find her to be safe and sound. You can then report to Jack and complete the second mission.
You will now unlock the third and the most challenging part of the quest, wherein you are entrusted the task of finding Jack's insane brother in some remote asylum, before the raiders get to him.
Jack's brother is mentally unstable due to the influence of some lost artefact and you are required to retrieve the same. Just head over to the bottom level of the Insane Asylum and take out the last raider who is kind of a miniboss in this quest.
You will then need to decide whether to kill or spare Jack's brother. If you spare him then you will not be able to retrieve the Gamma Gun or the artefact. So, killing him would be your best option to complete the mission.
You need to flip all the four switches in sequence and Jack will activate some zeta radiations that will instantly kill his brother.
Now just go and talk to Jack and he will assure you that he can recover something useful for you from the artefact. You will be asked to see him again after one week to get the newly crafted weapon.
You can bide your time doing some random quests or the quickest method is to trigger the timer by sleeping on any of the beds in one of your settlements in the game. Tip: You need to sleep for 24 hours and repeat it for seven times to move the time ahead by one week.
Finally, you will get the quest item notification, prompting you to see Jack. You could find him anywhere on the map including his house and the asylum.

Check out the Gamma Gun's weapon stats including damage, ammo capacity, range, accuracy, weight, as well as price in Ross's intriguing gameplay video below: