>Are you getting this from ChatGPT or something?

Woah hey, take that back. But I concede both that I kinda went off on what I am interested in, and you might know more about this than I do. And that I was half replying to you, and half explaining why lead is used (neither very well).

I don't actually remember what was at the center of the copper pellets, but I remember concluding that whatever it was, it was harder and lighter than lead and the copper wasn't enough to make it grab the rifling properly. I've also tried zinc tipped pellets with a plastic base. The main concern with air rifles internally is grabbing the rifling, which is what lead excels at. A secondary concern is the resulting lead dust eventually fouling up any mechanisms is uses for repeating. A third, I guess, would be the pellet deforming, which is a case against lead.

I assumed (incorrectly) that the same would apply to most firearms

Ah, Airguns. That makes sense. If you have any more of those pellets, it might be worth taking a pair of cutters to one and seeing what is inside. Maybe copper washed zinc, which would be funny?

Airguns have such a wide range of wildly different criteria, it’s hard to generalize. Ballistic performance (by any definition or subdivision) is pretty much never a primary concern however though?

At least compared to regulations/compliance, cost, entertainment value, safety (aka anti ballistic effectiveness haha), etc.

Airsoft being a prime example. But even the ‘diving cyclinder powered’ Airguns, which can be quite effective by some measures, are still ~ an order of magnitude less pressure than a 45ACP, which is about as low pressure as a firearm cartridge can get? (And one of the first smokeless cartridges still in wide use - well over 100 years old now)

Most airguns are going to struggle to be usefully accurate or powerful at 100 yards (or even make it at all that far), and that’s kind of the minimum range for any rifle. Most rifles with practice can reliably hit targets at 800 yards, and can be lethal out to 2000-3000 yards.

Most handgun users will struggle past 15 yards, but it is rarely the gun. With practice and a competent shooter, almost any handgun can reliably hit ‘gongs’ at 100 yards, and are quite lethal out to at least 800 yards.