Jon Schaffer — the founder of heavy metal group Iced Earth — is now in federal custody, and as it turns out, he was one of the more hardcore rioters who raided the Capitol … according to the FBI, anyway.

The feds say Schaffer turned himself in Sunday in Indiana, where he faces six charges in connection to the Capitol insurrection … including engaging in an act of physical violence in a Capitol building, violent entry and disorderly conduct in a capitol building, among others.

There’s also this … the FBI say, “Schaffer was allegedly among rioters who sprayed Capitol police with ‘bear spray.'” You might’ve seen some of that going on Jan. 6 — members of the Trump crowd were getting hosed with pepper spray, but were dishing it right back.

One such individual who was caught on camera unloading his bear spray nozzle has been…