Was billy the kid a Wild west gunslinger?

If you mean did he have solo gunfights, no. Billy the Kid was a key figure in the Lincoln County War in New Mexico. He fought for the Tunstall faction. Credited with 21 killings at the time of his death, there are only four verified kills that can be credited to his. He participated in shootouts involving dozens of men on both sides which accounts for the 21 total deaths. The Tunstall posse were known as The Regulators. In their minds they were fighting a corrupt sheriff and the MacSween political faction. Naturally, the opposing side thought the Tunstall faction were the outlaws. Billy achieved national fame by breaking out of jail where he was awaiting execution. He was later killed by former friend Pat Garret, the new sheriff. Whether Garret knew Billy was unarmed or not has long been a point of controversy among westernologists.