Though not well known, alternative trigger designs utilizing the thumb, rather than the index finger, are not as new an idea as many believe when first seeing the Iron Horse Rifle. In fact, thumb triggers date back to 1870 with the Italian Thumb Trigger 11mm Trials Rifle created by Glisenti-Pieri of Brescia.
Nearly 30 years later, it would be Winchester that filed for the first patent related to the "thumb trigger" in 1899 and 1905. Winchester introduced a rifle chambered in .22 short, lr and xlr, and they indeed marketed it as a more accurate rifle. The plinking and small game rifle was released in 1905 and hit nearly 80,000 units in sales by the year 1923. Despite steady sales, the rifle was discontinued in 1923 after William Wirt Winchester passed away, along with many other models the Winchester Co. had come out with prior.
In 2015 the founder of Iron Horse Firearms, Ryan McDonald picks up, and adds to, where Winchester left off. Arriving at the thumb-fired rifle independently, and Ryan being a former U.S. Marine, he had envisioned the use of the thumb actuated trigger on the government issued M-4 rifle. Ryan had imagined as Oliver Winchester may have, that pressing down on a trigger may lend to less windage errors, i.e., greater accuracy. Over the next few years Ryan would research into the viability of his idea and with the results he'd launch Iron Horse Firearms.
In early 2019, the thumb fired rifle was used in a controlled study, and generated strong evidence suggesting it to be more accurate. The data illustrated and average shot group reduction of 28%, meaning it was more accurate than near identical AR-15's, sporting traditional triggers. By summer 2020 the first models would be introduced to the market; the Iron Horse DMR, and SPR. Leading up to the launch Iron Horse collaborated with Mantis Tech to once more try to determine if there were any advantages to the thumb operated trigger system. Using a small group of both novice, and experienced shooters, we collected shot data using an accelerometer to measure movement introduced through trigger manipulation. Note the difference on the plot maps below.
Traditional AR15 Lower:
Iron Horse Thumb Operated Lower:
Thumb Fired Rifle Advantages:
- The thumb is more flexible and agile than fingers lending to increased feel
- The thumb better resists freezing temperatures
- The thumb is the most independent digit i.e., fingers move together and the thumb's movement is easily isolated.
- Fingers, especially the index finger is prone to being injured, and it is estimated 65,000 Americans lose the use of their index finger annually
- Not having a traditional trigger to contend with, the shooter's wrist can be set in a manner similar to a pistol for increased recoil control, and more accurate follow up shots
Iron Horse Firearms' thumb trigger is now being widely adopted by the public and testing within the military is garnering great results. Iron Horse is encouraged to see the enthusiasm and growth around the remastered thumb fired rifle.