Failure to drop the hammer can occur when the overtravel screw on a custom trigger is turned in too far, preventing the trigger from moving far enough rearward to trip the sear. The overtravel screw should be adjusted to allow a generous amount of overtravel; too tight an adjustment may result in the sear blade nicking the half-cock notch on the hammer as the hammer falls. Full rearward trigger movement may also be blocked by an improperly fitted grip safety (see the “Safety” section below).

Light hits or misfires can be caused by: gunk in the firing pin tunnel; a reduced-power mainspring (sometimes installed to lighten the trigger pull); or a timing problem with the Series 80-style passive firing pin safety. In the Series 80 mechanism, pulling the trigger activates a linkage that raises a wasp-waisted plunger in the slide just enough to allow full firing pin movement. If the timing of the linkage is off, contact may occur between the firing pin and the plunger, diagnosed by dings on the plunger.

Finally, the trigger must be able to move freely in its track in the frame. The bow should be deburred or reshaped if it drags in the frame or binds on the gun’s magazine.

Safety
Functioning of the M1911 thumb safety must be checked whenever a new sear, hammer or safety is installed. First, with the pistol cleared, cock the hammer, rotate the safety to the “safe” position, and pull the trigger. You should feel no trigger movement of any sort. Next, with the trigger finger off the trigger, move the safety to the “fire” position. The hammer should not fall. If the thumb safety passes these two tests, it should be working properly. If any doubts persist, have a pistolsmith examine the gun.

For reliable grip safety function, the trigger stop part of the safety must be shaped to allow trigger movement when the safety is pressed, and block the trigger when it is not. The safety must also rotate freely and not rub on the mainspring housing or the frame. Moreover, excessive pressure of the right-hand finger of the sear spring on the grip safety can cause the safety to bind the trigger bow, preventing proper trigger return.

Finally, as noted above, malfunctioning Series 80-style safety mechanisms can be diagnosed through dings on the safety plunger. Correcting this problem, or any other safety problem with an M1911 pistol, should be left to a gunsmith.

Miscellaneous
Occasionally, the slide stop may pop up and lock the slide back before the magazine is empty. The fix is to put a tiny dimple in the face of the slide stop that is engaged by the frame-mounted plunger when the stop is in the lowered position.

Easy magazine insertion may be impaired by an overtight or gritty magazine catch, and it is rectified by polishing the underside of the engagement ledge and deburring the magazine catch opening in the frame. The magazine may also bind on overlong grip screw bushings that protrude into the magazine well. A little careful filing usually corrects this.

With a custom M1911, reliability issues can arise from a too-tight slide-to-frame fit, an insufficiently relieved barrel bushing (causing vertical barrel springing), or binding of a custom-fitted barrel’s hood or upper and lower lugs. The close tolerances in such guns may cause the slide to drag on the frame when the gun gets dirty or dry, and even produce galling, particularly with all-stainless-steel guns.

General reliability may also be enhanced by extra-tough disconnectors, extractors, firing pins and hammers that exceed original specifications for strength and longevity and are offered by many aftermarket manufacturers. Correspondingly, function may be compromised when no-name, economy-grade parts of unknown origin are used.

Of course, no matter what reliability work has been done, the M1911 must be kept clean and well-lubricated. Regular maintenance is also required, such as replacing recoil springs at regular intervals.

Finally, note that not all M1911 slides, frames and other parts adhere to original military specifications. Feed ramps with improper angle or depth, breechfaces that are offset or of the wrong width, barrels with incorrectly cut throats or chambers, and many other dimensional discrepancies can cause reliability issues that are difficult to both diagnose and address.

The above does not by any means exhaust the list of M1911 reliability issues that may be encountered. For more information on M1911 function, maintenance and modification, consult “The U.S. M1911/M1911A1 Pistols: A Shop Manual,” Vols. I & II, by Jerry Kuhnhausen; the “Wilson Combat 1911 Auto Maintenance Manual;” and the M1911 DVDs from American Gunsmithing Institute, Wilson Combat, Ed Brown and others. Such books and DVDs are usually carried by Brownells and MidwayUSA. Be aware, however, that no article, book or DVD can substitute for the experience and training of a skilled pistolsmith.

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