http://www.revolutionarywarjournal.c...unable-to-use/
инструкция по расклепыванию (если повезет) и правильному заклепыванию.
В первой трети 17 века стали делать vent-piece / touchhoule bushing вывинчивающиеся затравочники, потому как быстро выгорали - и после достижения "недопостимого размера" - в переплавку
To unspike a piece:
If the spike is not screwed in or clinched, and the bore is not impeded, butt in a charge of powder of 1/3 the weight of the shot, and ram junk wads over it with a handspike, laying on the bottom of the bore a strip of wood with a groove on the underside containing a strand of quick-match by which fire is communicated to the charge; in a brass gun, take out some of the metal at the upper orifice of the vent, and pour sulfuric acid into the groove for some hours before firing. If this method, several times repeated, is not successful, unscrew the vent-piece, if it be a brass gun, and if an iron one, drill out the spike, or drill a new vent.