Even 275 would not hurt brass
Optimal Case Temperatures for Successful Annealing
Brass is an excellent conductor of heat. A flame applied at any point on a case for a short time will cause the rest of the case to heat very quickly. There are several temperatures at which brass is affected. Also, the time the brass remains at a given temperature will have an effect. Brass which has been "work hardened" (sometimes referred to as "cold worked") is unaffected by temperatures (Fahrenheit) up to 482 degrees (F) regardless of the time it is left at this temperature
Regarding tumblers, I made one myself with a 1/2 hp motor, pulleys, and pvc pipe.
I can clean 100 pounds worth and the motor is not working hard.
You should NEVER put brass in an oven to dry. Every reloading manual states this for a reason...


















































