Why did Tybalt have all bullets but one removed from his gun and why mercutio reach for Romeo to do the same?

There is no evidence from William Shakespeare's play "Romeo and Juliet" to suggest that: (a) Tybalt's handgun had any of its ammunition unloaded; or (b) that Mercutio attempted to get Romeo to unload any handgun.

Would you like to know additional context about guns during that time period?