Tom - the minimum wall thickness is the major concern with the barrels- the other thing to do is to hang the barrel by the hook from a finger or a loop of string and "ring" them - flick a finger nail against the barrels and you should get a soft clear bell like tone. This lets you know the solder is solid
as for shells, A lot of us like RSTs in the older guns
http://www.rstshells.com/
lower pressure and recoil