Does anyone know the twist of a .357 AEA Challenger barrel?

Stick a cleaning rod in with a bore brush or mop attached into the barrel.

Make a mark on the rod both where the rod enters the barrel and one towards the handle.

Slowly push it in until the rod makes one full revlution (the mark near the handle spun around once and is now where it started)

Make another mark where the rod enters the barrel.

Measure the distance from the first mark to the second mark.

10 inches? 1:10 twist (just an example)