Beowulf. Nice cannon. Try temps around 800. When I cast 2.25” projectiles, I consider the 1st five or so to be sacrificial used to warm the mold which is also preheated. Just put em back in the pot to re-smelt. Watch for any temp drop. Can you recover any projectiles to view rifling engagement? I learn a lot from the recovered rounds. Some places may frown on digging up the berm. Does your bottom pour allow a quick enough fill?
Ammunition is like firewood. The more you have, the warmer you feel.