It depends, but most ammo is at least partly lead.

Your standard ammo is likely what gets called fmj, full metal jacket. That's a bullet made of lead and wrapped in some other metal.

There is ammo that's only lead. Shotgun ammo is fairly commonly lead pellets unless it's meant for bird hunting.

There's various lead only bullets as well. I still have a few hundred rounds of wadcutter, which is a type of bullet shape, that's lead only. I never shoot it any more because, well, pure uncovered lead. That and I'm not fond of the load they have, but that's not why I stopped using it for target practice; it is why I wouldn't shoot it for anything else unless I had nothing else left though.

You can get other materials, but lead has a good weight at any given caliber that's hard to duplicate.

That being said, my carry handgun stays loaded with frangible rounds that have zero lead in them at all. I have backup ammo for it, but the five or six magazines I keep handy are all non lead except maybe one? Could be two; you have to practice with what you'll actually be shooting if you have any sense. So I tend to rotate through, but the brands I prefer have been hard to get, so I have some hollow points in a couple of magazines still.

Anyway, yeah, if you roll up to anywhere that sells ammo, chances are high that you'll have to walk out with something that has some amount of lead in it.