"switching what out"? A light hammer strike is generally caused by a defective hammer spring or incorrectly assembled hammer.
Did you build this? If so, how much of it did you put together? You should take that ATI crap and throw it in the trash. And an H2 really isn't need for a midlength carbine. it sounds as if part of the problem was failure to go fully into battery. If the weapon is not fully in battery, it will not fire.

