With a conventional sidelock, the trigger is a separate unit that must make contact with the spur on the sear to release the lock’s tumbler thus allowing the hammer to fall. Because of the “looseness” and tolerance between the trigger and sear there was quite a variation in trigger pulls between guns even of the same design and from the same maker. Achieving a really light, crisp trigger release in the typical sidelock rifle with a single trigger required the skills of an advanced gunsmith. All that equates to added expense to the rifle. Which, of course, spawned the creation of the double set-trigger.
However, when the hammer and trigger are directly connected, as in most underhammer designs, it is much easier to achieve a nice release of the trigger without a double set mechanism.
All that said, I have to admit that double set-triggers still intrigue me and I am guilty, too, of designing them for underhammers that just don’t need them. It’s a dichotomy that plagues me because while the double set mechanism intrigues me with the possibilities of clever design, it also violates my sensibilities regarding an adherence to the KISS principle in underhammers. Unless, of course, maybe I was making another long-range or offhand schuetzen rifle! That would be really cool and the set-trigger would be a real advantage.
One of our readers, Jonathan Bumstead, who is also an underhammer designer, has shared with us his latest creation in which he, too, succumbed to the allure of the two-trigger system. While he hasn’t shown us how he did it, I am really curious because anyone who can make a set-trigger mechanism that will consistently work in such a small space is on to something and I, for one, would like to know more!
Check it out. Remember that clicking on the photos will enlarge them for a close-up view. Just click the Back arrow on your browser to return you to the text.
I had a simple idea and sketch, but basically I built it by first making one piece then making the next and fitting them together and so forth in progression. The second version will be made using all the experience (translate that as, "mistakes made") that I gained building the first one.