About 99%. Lead is an inexpensive metal that is soft and dense- 3 criteria for bullets. Most will be made of lead- if not entirely, they will have a lead core covered by another metal, such as copper.
A better question would be which do NOT have lead. A small percentage of rifle and handgun bullets are solid copper, bismuth, or some non-lead metal. Shotshells used for waterfowl are loaded with non-lead shot- steel, bismuth, or iron/tungsten alloys. But MOST bullets are still lead. It may be covered by a gilding metal jacket, but it is there.
Blue bullets are bullets are high quality Polymer Coated Lead Bullets.
Yes, may people use lead bullets for a variety of purposes.
Yes. Lead bullets do not wear out the rifling inside the barrel as fast as steel bullets. Still, many people use steel-jacketed bullets . . .
Bullets
Bullets can be made from many materials including wood, steel brass, copper, lead, tungsten, bronze, plastic, etc.
Usually they aren't. Lead, or lead in a copper shell (a "jacket") is the most common choice for bullets. Bullets CAN be made of mild steel, usually also copper jacketed, and it's usually done because of concerns about the lead from the bullets causing pollution. Mild steel is one of the less expensive replacement options for lead in bullets.
Normally - lead.
Most bullets are made from lead. Some will have copper jackets around them, but the bullet itself will be lead.
By heating the lead into a liquid and pouring it into a mold
Barnes Bullets is a company that makes bullets. Their bullets are lead-free. Barnes Bullets supplies bullets to the military as well as to the hunting community and to law enforcement agencies.
lead.