however I am a manufactureing jeweler and work with non ferous metals evey day and I can tell you of brass, that when purchased as sheet, cold rolled (nearly all is) it is at its hardest state. in that state what you have really is "work hardened" brass, i.e. extruded, rolled or hammered, to compress it's moleculer density. Try this experiment. Take some 1/16 inch brass, three strips as close as possible in width. On a piece of charcoal or soldering brick, heat on up to a dull red and cool under a half of an aluminium coke can; in undisturbed air. On the second one, evenly hammer the piece with a real smooth chaseing or ballpeen hammer, not too rounded, on both sides lightly. Leave the third in it's cold rolled state to test against the other two. I will promise you the one you hammered is by far possesed of the most "spring". If you have a surface grinder, you could hammer out an eighth inch thikc piece then surface grind it to thickness desired in which case, you must hammer evenly so as not to distort or warp, then you've only the hammer marks to deal with...most manufactures just use it cold rolled although perhaps a thousandth or two past "just hard". I have a sheet & wire rolling machine here in my shop and can, in just a few thousandths, increase sheet brass hardness / spring by quite a bit.
regards, mitch
