Double-Set Trigger Troubleshooting - Rear Trigger Won't Hold

[smithy]

A client brought in an impressive antique single-barrel muzzleloader, evidently crafted many years ago for target shooting. It features dual triggers, but the main spring seems loose, and the secondary trigger clicks without engaging. This condition is quite typical for rifles of this vintage.

A single barrel muzzleloader with two triggers is commonly referred to as having a double-set trigger system. In this system, one trigger (usually the rear one) is used to set the other trigger (the front one) for a very light pull, allowing for a more precise shot when needed. The front trigger can sometimes be used independently for a normal trigger pull if the rear trigger isn't set. This mechanism is particularly useful in target shooting but also has applications in hunting for a more controlled shot.

[smithy]

If the rear trigger of a double-set trigger system clicks but doesn't hold, various problems might be at play (see below). A quick visual check showed no parts were completely broken, but the spring seems weak, so we'll start there and work backwards. It's possible there isn't enough tension in the system to maintain the trigger in its set position. Additionally, the trigger guard looks mangled, likely from previous difficulties in removing the pins, hinting at potential alignment issues. It would be wise to realign, reseat, and correctly set the triggers.

Potential Issues:

• Improper Adjustment: The set screw might not be adjusted correctly. If the screw is too loose, it might not engage properly to hold the trigger in the set position. Conversely, if it's too tight, it might not allow the trigger to set at all. Adjusting the screw carefully can sometimes resolve this issue.

• Wear and Tear: Over time, the parts of the trigger mechanism can wear down, especially the contact points between the triggers or the springs. This can lead to a failure in holding the set position. Check for signs of wear or if the parts have lost their hardness, which could necessitate replacing or re-hardening the parts.

• Dirt or Debris: Accumulation of dirt, powder residue, or other debris can interfere with the smooth operation of the trigger mechanism. Cleaning the trigger assembly thoroughly might solve the problem. Sometimes, removing the lock and operating the triggers out of the gun can help in identifying if dirt is the issue.

• Spring Tension: The springs involved in the set trigger mechanism might be too weak or have lost their tension over time, leading to improper function. This could require either adjusting or replacing the spring. The adjustment screw behind the rear trigger, if present, controls the spring tension; if this screw is adjusted incorrectly or damaged, it might not allow the trigger to hold.

• Misalignment or Damage: If parts of the trigger system are misaligned or damaged, the rear trigger might click but not hold. This could be due to improper reassembly after cleaning or from physical damage. Inspecting the trigger for any signs of misalignment or damage, perhaps by disassembling the mechanism, can pinpoint this issue.

• Setting Procedure: Ensure that the setting procedure is being done correctly. Sometimes, if the hammer is not in the correct position when setting the trigger (like not at full cock), the trigger might click but not engage properly. The rear trigger should generally be set before cocking the hammer to full cock.

[smithy]

Our hypothesis proved accurate. The trigger-return spring, made from small-diameter wire, had deteriorated over time, lacking the strength to maintain the necessary tension for the set trigger. I crafted a replacement from music wire, reassembled the mechanism, and now everything operates as intended. These dual triggers should now set properly even when detached from the firearm and the locking mechanism.

front-spring.png (540.26 KiB) Viewed 15 times

[smithy]

For an old target muzzleloader equipped with dual set triggers, the specific part names can vary slightly based on the manufacturer, but here are the common components you'd typically find:

• Front Trigger: This is the primary trigger that you pull to fire the gun once the rear trigger has been set.

• Rear Trigger: Also known as the set trigger, this is pulled to 'set' the front trigger, making it very light and sensitive for accurate shooting.

• Trigger Plate: The base plate where the triggers and related mechanisms are mounted.

• Sear: Engages with the hammer or lock to hold it in place until the trigger releases it. There's often a main sear and a set sear in dual set trigger systems.

• Set Screw: A small screw used to adjust the tension or the 'set' of the trigger, allowing for fine-tuning the pull weight.

• Trigger Return Spring: A spring that returns the trigger to its initial position after being pulled.

• Stop Screw: Can be used to limit the travel of the trigger or adjust its position.

• Pivot Pin: The pin around which the trigger moves.

• Sear Spring: Provides the necessary tension to keep the sear engaged with the hammer until the trigger is pulled.

• Fly: A small part in some dual set trigger systems that helps in setting the trigger by moving out of the way when the rear trigger is pulled, allowing the front trigger to engage in a lighter pull.

These parts work together to provide the functionality of a dual set trigger system, where the rear trigger adjusts the front trigger's sensitivity for precise shooting.