Ooh, I could see that, autocorrect error instead of unfamiliar term.

/u/phiggy if that's what you meant, then it depends. If it was fired in the direction of travel, it would have an increased apogee but would eventually slow down from atmospheric drag and re-enter but it could take years because it's dense.

If it was fired 'backwards' to the direction of travel, it would probably take a little under an hour to hit the ground assuming it didn't vaporize on re-entry (lead might not fare as well as another bullet materrial? I don't know what they fired). Going from memory, it was Nudelman 37mm that was adapted for use in space and a quick Google says that it had a muzzle velocity of just under 700 m/s. A re-entry burn for a vehicle in LEO is usually like less than half of that so that should be enough to put the perigee inside the atmosphere where it would slow until it was falling straight down at its terminal velocity.