Well, see how it fires off the bat. There are several different kinds of sig 19s being sold. I got the sig 19b with the nzonic cap. Id definitely remove the spring comes in the top cap on that version to expose the brass pin. If the mod fires fine, great. But i found that it would only fire if i pressed the button a very specific way, which is annoying to do after a while. So first, try flipping the battery (+ side down) and see if that makes the misfires go away. If not, then do this modification. However, if u are lucky enough to get on without the glued switch, and are able to unscrew ur switch completely, theres is a sig 19 tips and tricks thread here with a million different methods, some easy, some more intricate, to eliminate misfires. Theres another thread detailing how to take apart a glued switch, involving dremels, acetone, alcohol, boilijg water, pliers, a vise, a bunch of things that could potentially damage ur mod in the process. So if u have the glued switch, and have misfires out of the box even with flipping the battery, then try my method. U should be able to fire consistently like i show in the vid.
My method lowered misfires and also increased my vapor production because of the copper's conductivity assiting the stainless steel mod. So id do this even if there werent misfires to improve my vape quality. But like i said, u may be lucky and have a non glued switch, much easier to mod that if necessary. Good luck! With modification, it is my all around favorite mech currently (i only have china clone mods though)