I looked up the unique GUNS on the NV wiki page and decided to collect a bunch of them, I have All American, Gobi Campaign Scout Rifle, Big Boomer, Dinner Bell, Ranger Sequoia, The Ratslayer, La Longue Carabine, and the Mysterious Magnum. Now, to get some of these I had to kill these people: Chief Hanlon, Corporal Sterling, Old Lady Gibson, and The Lonesome Drifter. The first two were NCR characters, but I took them out with a silenced sniper rifle so that I wouldn't get any infamy with the NCR, but I failed a quest after killing each one, four in all. Will killing these people do anything to the ending? Have I ruined my character by doing this?
Edit:
Chief Hanlon - Location: Camp Golf - Quest Failed: Return to Sender
Corporal Sterling - Location: Camp McCarran - Quest Failed: I Don't Hurt Anyone
Old Lady Gibson - Location: Gibson Scrapyard - Quest Failed: Come Fly With Me
The Lonesome Drifter - Location: Near El Dorado Gas & Service (by a billboard after you activate the Talent Pool quest) - Quest Failed: Talent Pool