Thread: BSA 3-lever triggers (Royal, Hunter, etc.)

One of the triggers I cut my teeth on when I started professional gunsmithing more than 50 years ago was the 3-lever BSA trigger as found on the Royal, Viscount, Hunter, and early Majestic rifles, all of which feature the safety on the bolt shroud. Now a lot of these older (and high quality) BSA's are becoming popular for custom rifles and I am getting more and more enquiries on these old triggers so I though I would do a sketch to better explain how they work and how to adjust them. By modern standards they are fairly complex for a roll-away sear system, having 4 major components as compared to 2 in most modern triggers. As can be seen on the attached sketch pressure on the trigger (lever 1) moves the trigger lever (lever 2) to release the sear lever (lever 3) which allows the sear to drop, releasing the striker. The critical engagement area is the outer ends of the trigger lever and sear lever where they meet. The two engaging surfaces should have a smooth polish but be dead flat (no curves or rounded edges) with sharp edges. Stoning the surfaces to alter the angles is fraught with danger without specialised knowledge. The rigger can be adjusted for weight of pull, one or two pressures, and sear engagement. The trigger weight adjustment should not be adjusted until the lock screw at the rear of the trigger is slackened off, then small adjustments made to the weight screw, checking frequently by dry firing with a good accurate spring gauge. The ideal weight is between 2.5 - 3 pounds (1.2 -1.5 Kg). Once the desired weight is set then tighten the lock screw. The take-up screw can be slackened off to give a small amount of pre-travel (double pressure) for those that prefer it. The ideal setting is when the tail of the trigger just makes contact with sear lever which will also give a safe sear engagement. Over-tightening of the take-up screw will reduce the sear engagement which could cause the rifle to fire prematurely if the safety catch is disengaged. I do recommend that all trigger work is undertaken by skilled and knowledgeable gunsmiths, and hopefully this small contribution will help the younger ones of them become familiar with system. Note that if the mechanism is dissassembled then small slave pins are needed to install the trigger and sear levers with their springs attached. Go carefully and ask for help if needed!