How hot will the outer drum get on a rocket stove/heater?

I have not yet put a bigger drum over my rocket heater/stove. How hot will the drum get? Will it be good for sitting around at night and getting the heat to keep you warm? or will it not throw out that much heat?

I assume you are talking about a barrel of an insulated heat riser? If so, it gets plenty hot, like a barrel stove. I have measured 900 F at the exit point! Of course the top(cooking spot) gets red hot.