By Les Bengtson
When the trigger is tuned , the engagement surfaces of the hammer (hooks) and the sear (nose) are polished and mated together to produce a clean, lighter weight of trigger pull. On competition pistols, the weight of pull may be quite low, with some shooters running trigger pulls of under three pounds. For “practical” competition and, most especially, for carry use a trigger pull of four to four and one half pounds have proven the best and longest lasting.
When the trigger job is accomplished, both the hammer and the sear are polished and the proper engagement of the mating surfaces is set. After that has been done, the three leaf spring is bent to provide the proper tension on the sear and disconnector. And, here lies the problem. These lighter spring pressures do not put as much force on the sear and disconnector as the excessively strong factory conformation. In most cases this is not a problem, but this change must be understood of one is to get the longest life from a trigger job.
When the trigger is “pulled”, the trigger bow moves backwards until it engages the disconnector which moves backwards and presses against the forward legs of the sear. When sufficient pressure is applied, the sear rotates around the sear pin and moves out of engagement with the hooks on the hammer, allowing the hammer to move forwards and strike the firing pin. As the slide moves backwards to eject the fired case and to chamber a new cartridge, the disconnector is forced downwards, from its slot at the rear of the slide, which forces it out of engagement with the sear. When the trigger is released, it moves forwards, under pressure from the leaf spring at the rear of the disconnector, until there is sufficient room for the disconnector to move forwards and rise upwards to again mate with the sear. Thus, when firing, the trigger is under constant pressure from either the trigger finger or the disconnector segment of the three leaf spring. Under such circumstances, the hammer should never fall to the half cock position unless there is a basic problem with either the hammer, the sear, or both.
When the pistol is loaded, however, the trigger is not commonly restrained and is free to move backwards and forwards -- it is free floating within the frame. This can, especially when a heavy steel trigger is used (such as the original 1911 “long” trigger) cause what is called “trigger surge”. This means the free floating trigger is bounced backwards with sufficient force to just trip the disconnector against the sear sufficiently to move the sear out of engagement with the full cock notch of the hammer and allow the hammer to drop to the half cock (safety) notch. This is most frequently encountered when a new magazine is inserted and the slide allowed to move forwards by moving the slide stop downwards to its normal position. This puts a sudden forwards acceleration on the slide which, as it stops, transfers the movement to the frame. The free floating trigger, due to inertial, does not move and bumps the disconnector with sufficient force to, perhaps, cause the hammer to fall to half cock. This is a problem which has been known and understood for over half a century.
There are two basic methods of preventing this problem:
The first method was commonly used at the NRA 2700 matches. The magazine was loaded into the pistol with the slide locked back (as required by match rules), the trigger was held to the most rearwards position, and the slide stop was pushed downwards out of engagement with its notch in the slide. By holding the trigger back, there could be no trigger surge.
Since the advent of “practical” shooting, one is not allowed (by match rules) to touch the trigger when loading the pistol. Hence, two things have happened. The first is the production of lighter weight triggers which, while they still surge, do not have as much inertia when doing so. Most triggers made today are of this lighter weigh conformation. The second thing which has been done is a technique item. When loading the pistol, rather than using the slide stop to release the slide forwards, the slide is manually grasped , moved rearwards sufficiently to cam the slide stop out of its engagement notch in the slide, and released. This allows it to move forwards in a more consistent and controlled manner and significantly reduces the possibility of trigger surge.
In the “modern technique” the slide stop is used to hold the pistol open for inspection, but is not used for loading. The grasping of the slide, moving it fully rearwards, then releasing it is used for initial loading and reloads. This same basic motion is, also, used for two of the malfunction drills -- a “smoke stack” malfunction and a failure to fire malfunction (also called a “tap-rack-bang).
Anyone owning a tuned 1911 series pistol needs to understand these basic concepts and decide which to use in their shooting. Practice demonstrates that a tuned trigger will hold up for tens of thousands of rounds with the proper loading/reloading technique is used. The tuned trigger can, also, be destroyed relatively quickly by using incorrect technique which causes the sear to be damaged by falling into the half cock notch.
Copyright 2012/2015 by Les Bengtson