What was made once can be remade. The only question is the thread diameter and pitch. Lathe turned threads can be made to any diameter and to any pitch the lathe has gearing for. Most likely the pitch is metric.

Back when, copper-berillium was the in thing for nipples. It is hard enough not to batter and springy enough not to batter the hammers (and hammers can be an expensive repair). Fitting for #11 caps should be no challenge 'tall.