Metal Drums

o.o A w.i.p. of something I've been painting lately, metal drums and rusty versions, and both open and closed.  I am uncertain of the bottom, but the top of the barrel is pretty good.  If you wish to give feed back, please do, as I am still in the process of learning how to handle forms.  This is my current lesson, metal and round.  Lucky, I think my shading is good, though my rings could use a tad bit of work.