I could look it up but the "German Silver" used in the barrel was clean white bronze ingots roughly 65 copper, 25 nickel, 5 tin, and the rest lead and zinc. The blank was poured solid with a bore 1/3 the breech. No breech plug, made along the same "guidelines" for bronze cannon.
When one looks at how original pieces may employ brass barrels with brass threaded breech plugs (steel threaded into brass) and larger bores relative to their breech are your comments about blowing myself up really necessary?