Barrel coolant

[Rocky Raab]

Plain old water works as well as anything.

When I'm really hotting up a barrel on prairie dogs, I keep a liter bottle of water with a "bartender's spout" installed. I just tip the muzzle down and pour an ounce or two into the chamber with the spout. It'll flash dry if the bore is hot enough, and no harm done.

If any liquid is left, I can always drop a BoreSnake through it.

At the range, I drape a wet towel over the barrel with the bolt open and the muzzle up a bit. The bore will "chimney" cool air in through the breech and the towel will both shade and evaporative cool the exterior.

Unless you shoot it until it's positively glowing, you won't cause any problem with sudden cooling, however it's done.