I didn't buy from a company that bought a full-page ad in American Rifleman claiming:
RUGER
OUR CRAP BREAKS IF YOU USE IT/QUOTE]
Give me any gun and enough ammo, and I will break it. Everything will break, even ak47s. A sight flying off is considered normal wear and tear to me, not a manufacturing defect. If it was considered a manufacturing defect, then you might as well consider anything that happens with the gun a manufacturing defect (including but not limited to springs that are wore out/broke, rifling thats wore out, wore finishes, etc).
If your going to base your satisfaction with a gun company on the fact they give you any part you need for free, then Ruger let you down, and you should go to a different company. If your going to consider the front sight coming of a used gun as a horrible thing that shows the gun is unreliable, and not worth owning, then you might as well give up on firearms since no firearm is immune from breaking parts.