Lead is one of the most wanted junk in Fallout 76.
It's used to craft most of the ammo.
If you are going to smelt Lead to craft ammo you will need a lot of Acid.
Items that gives you Lead after you deconstruct them are:
1. Lucky Hole Mine
Lucky Hole Mine is the best way to farm Lead, it is located in Savage Divide, near Fort Defiance.
But before you go there make sure you that you've fully equipped Excavator Power Armor.
This PA beside allowing you to carry more, allows you to mine 4x more veins when wearing it.
Location of Lucky Hole Mine
Gym equipment is second best way to get Lead.
There are several gyms in Appalachia, three of them are in Silos and one is at Charleston Fire Dept.
Every barbell, dumbbell and curlbar has different ratio. Here is the list how much each contains lead: