I was surprised to find that the Stevens single-set trigger is patented. James N. Fisher, May 7, 1907, US 852,942, assigned to the J. Stevens Arms and Tool Company. The drawings are very clear, as is the explanation of the function. I was unaware of this patent when I wrote up the trigger mechanism with Tom Meyer in the Jan-Feb 2006 Journal, but it does not appear that John Dutcher caught it either when he wrote it up in the Sept-Oct 1997 Journal. It certainly does not appear that the Stevens Company advertised it as their patent; perhaps they recognized that it was kind of a makeshift. The description of the functioning leaves no doubt that the trigger works off the overcenter rubbing or friction of the sear lever on a rounded projection on the sear spring, rather than a using a positive small catch or bent, like other set triggers. Set, it mimics the situation some hardball .45 shooters used to experience, where they turned the aftermarket overtravel screw on their trigger far enough to positively eliminate the last thousandths of overtravel, but, alas, not quite far enough to completely release the sear. The situation then resembled two razor blades balanced on their edges, with a live cartridge ready to go off when the inevitable imbalance finally slid them past each other. I argued in my writeup that there was no way this trigger would work well for very long. The spring cannot be glass-hard throughout and still be springy; if it was hardened on the end, that end would inevitably break off. The sear, on the other hand, would have to be casehardened, and this surface would wear the hump on the spring, meaning that the set screw for trigger engagement would need to be turned further and further in to maintain engagement. The trigger action would vary over time from acceptable to gritty creep to unexpected letoff (a "scare break" rather than a "surprise break"). Sort of like that other invention of the Devil, the Allen head screw. Two choices: the screw is harder than the wrench, rounding its facets off, or the wrench is harder than the screw, rounding the hexagonal socket out. I've never seen them exactly matched, at least on the teeny screws that the Allen head system is best applicable to. On the other hand, as Mr. Fisher notes, this trigger system does not need the extra length or width in the tang that other set triggers need, since the sear and trigger sit alongside each other and pivot on the same pin in the tang.
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