Weapon Bounty/Quest: The Stranger's Rifle Gunsmith sees you carrying around an intriguing weapons he's never seen before, and asks to take a look eager to learn about it. You hand it to him, and tell him that it was quite helpful during your days as an underclassman, but now that you're an upperclassman and battling lvl 20+ foes it's of no use anymore. He'll tell you that he can buff it up for you, but he'll need to learn a thing or two about it, and gives you a Weapon Bounty/Quest. He'll ask you to compete in the crucible and win 10 matches, but defeat will slow your progress. The Gunsmith now with a better understanding of the weapon stats that it's beyond any weapon he's ever tampered with before, and tells you that he's unable to help, but the Cryptarch might know a thing or two about it. You take it to Master Rahool, and tells that he recognizes some of the parts, but they appear to be modified greatly. He tells you that the FWC (Future War Cult) have come up to him with some engrams that contained curious items that looked almost exactly like some of the parts of this weapon. You approach the FWC and ask them about the weapon, but upon seeing it they become pissed off, and demand to know how you got the weapon. You tell them about the Exo Stranger. They refuse to help you upgrade the weapon, leaving empty handed you return to the Gunsmith and tell him about how the FWC appears to have some parts of the weapon as well as their refusal to help. The Gunsmith say that if he can some of those parts he might be able to upgrade you're weapon. The New Monarchy might be able to help you. You go to New Monarchy and tell them everything. They agree to help, and give you the next stage of your Bounty/Quest. Participate in the Crucible against the FWC and earn 10 melee based kills, death will slow your progress. Once done you return to the New Monarchy with odd weapon parts you had pick pocketed from FWC members. They tell you that the parts appear to be of Vex origin, and that the Cryptarch might know more. You go to the Cryptarch and he tells you that the parts are indeed of Vex origin, and that they might be from the Vault of Glass. Complete the Vault of Glass Raid. Once you complete the Vault of Glass Raid you discover that the parts are actually pieces of Vex Precursors and Oracles! You take them back to the Cryptarch who confirms that they're indeed Precursor and Oracle parts. You take the parts to Gunsmith who tells you that these parts will indeed buff up your rifle but because these are of Vex origin he'll need something to cleanse it. You give him a Mote of Light and he starts to work on it, and gives you the Stranger's Rifle (Rare) with a max damage value of 242. After leveling up your Stranger's Rifle you get message at post office from New Monarchy you request you're assistance. You answer their call and they tell you that they're concerned about what the FWC is up to with Vex parts especially since they're keeping it hush, hush. They tell you that a fire team from the FWC is about to leave for Mars, and they want you to spy on them. Go to Mars, and complete 6 scout missions on Patrol mode. Once completed you'll find that the FWC have set up camp at a Vex Spire, and appear to be analyzing it with computers instead of their ghosts. New Monarchy becomes even more suspicious as you're ghost relays the video to them live. They say that whatever it is they're doing they don't want their ghosts knowing about it. As the FWC continue their analysis of the Vex Spire the Cabal appear to attack the FWC. You get ready to intervene, but the Vex appear and fight alongside the FWC against the Cabal. This alarms the New Monarchy and orders you to return to the Tower ASAP, you're about to have a meeting with the Speaker and Vanguard. You return to the Tower, and meet with the Speaker, Vanguard and New Monarchy. They tell you that it is rather curious and alarming that the Vex are in alliance with the FWC but hostile with all other Guardians. They suspect betrayal and mutiny. They want to be sure though so they ask you to kill 30 guardians while invisible in the Crucible, you must make the kill while invisible or it won't count. Once you do this you report to them that you managed to pickpocket one of the FWC members and take a computer device that doesn't belong to the Vanguard's armory. They call in the Shipwright who tinkers with the device, and taps into FWC communications. As you eaves drop on the FWC you over hear them talking about something called, Project-Omega_12/B. A file is transferred over which your ghost intercepts and displays on the big screen revealing the schematics for a Vex unit they've never seen before. Everyone realizes that the FWC is responsible for the creation of the Vex, and make an order to take down the FWC. Guardians from Dead Orbit, New Monarchy, Vanguard, and Crucible rush the FWC's place but they find that every human, and awoken FWC member dead in their quarters. A dying awoken Titan explains that the FWC leader took a ship and the other Exo FWC members to Venus and is heading for the Citadel. You now have a new level 30 mission exclusive for this bounty/quest. Pursue the FWC and bring in their traitorous leader. Once you complete the mission the FWC leader will state that she created the Vex in retaliation for humanity putting the Exos into hibernation during the Collapse, and will stop at nothing to get revenge. You kill her, but the Vex continue her objective, Exterminate all organic life. Serve to protect all Exos. With the FWC tamed, you return to the Tower and given a gift in the post office. It's a mysterious element, from the Exo Stranger which you take to the Cryptach who says he's never seen such a thing before, but says it looks like something for your rifle. You take it to the Gunsmith who having learned lots from the FWC hidden documents and information uses it on your Stranger's Rifle upgrading it to Legendary Status. With a max damage value of 315.

But it's technically not an end game gun since the game is far from over

It really didn't make sense that it wasn't legendary. Hell it doesn't make any sense that the golden chests you find rarely had blue quality items. They honestly should of been legendary items, materials or engrams. Useful stuff.