Function checks after trigger work on a semi-auto pistol
Every trigger part on this site is designed to keep a pistol's safeties working, and every one of them can be installed wrong. A set screw turned a quarter turn too far, a spring cup not seated, a connector not flush: each is invisible from the outside and each can make a pistol fire when it should not. This is the checklist we run after any trigger, spring or striker change, written for a Glock and adapted for hammer pistols at the end. Run every step, in order, every time.
Before you start
Remove the magazine. Lock the slide back and look into the chamber and the magazine well; then put a finger in the chamber. Put all ammunition in another room. Point the pistol in a safe direction for every step below, at a wall that would stop a bullet, because the entire point of these checks is that you are not sure the pistol is safe yet.
1. Trigger safety
With the slide on and the pistol cocked, press the trigger from the side with a pen or a fingertip, avoiding the safety blade in the center. The trigger must not move. Press the blade flush and the trigger must move freely. A drop-in shoe that lets the trigger move without the blade pressed fails this test and comes off the pistol.
2. Firing pin safety
Remove the slide. From the rear, push the striker forward with a punch or a pencil. Its tip must not protrude from the breech face. Now depress the firing pin safety plunger on the underside of the slide and push again: the tip must protrude. Release the plunger and confirm it springs back flush on its own. If the striker moves forward without the plunger depressed, the plunger, its spring or the striker cut is wrong; stop.
3. Drop safety and the cruciform
Reassemble the pistol and rack the slide. With the trigger at rest, look through the ejection port at the trigger bar: the cruciform should be sitting up on its shelf in the housing. Pull the trigger slowly and feel that the striker releases only at the end of the pull, after the wall, not during take-up. If the striker releases early, pre-travel has been shortened too far or the cruciform is not on the shelf; back off the set screw and repeat.
4. Slam test
With the chamber empty and the trigger at rest, lock the slide back and release it with the slide stop so it slams home hard. The striker must not release; you should hear the slide close and nothing else. Repeat five times. Then hold the trigger back, rack the slide and release it, and let the trigger forward to the reset click: the striker must stay cocked until you pull again. A pistol that fires on slam has a drop safety fault.
5. Reset
Pull the trigger on the empty chamber and hold it back. Rack the slide fully and release it. Let the trigger forward slowly until it clicks, then pull again: the striker must release. If there is no click, or the trigger must go fully forward before it will fire again, the trigger spring is off its hook or the bar is not returning; if the trigger does not return at all, the trigger spring is broken.
6. Trigger pull gauge
Measure the pull five times from the center of the trigger face and average, as described in trigger pull weight explained. Confirm it is where you intended: about 4.5 pounds or more for a carry pistol, whatever you chose for a match gun. A reading far lighter than the parts should give points to a spring that is missing or a cup that is not seated.
7. Magazine and slide stop
Insert an empty magazine and rack the slide: it must lock back. Press the magazine release: the magazine must drop free. Insert a loaded-weight dummy magazine if you have one and repeat. A slide that does not lock back after trigger work usually means a trigger housing pin or the slide stop was not seated during reassembly.
8. Live fire
At the range, load one round and fire it, checking that the pistol cycles and the slide locks back. Then load two, then a full magazine. Fire at least 100 rounds of the ammunition you use, and for a carry pistol at least a box of the carry load. Watch for light strikes, failures to reset and doubling, which is two shots from one pull and means the pistol is not safe and must not be fired again until the trigger work is undone. Record the round count and the parts fitted.
Hammer pistols
On a 1911 or a DA/SA pistol, add these: cock the hammer and push it forward with a thumb, hard; it must not fall. Engage the thumb safety and pull the trigger; the hammer must not fall, and it must not fall when the safety is then released. On a 1911, hold the pistol without depressing the grip safety and pull the trigger; nothing should happen. Set the hammer to half cock where the design has one and pull the trigger; it must not fall. Then run the slam test, the reset check and the gauge as above.
When a check fails
Stop, do not fire the pistol, and undo the last change. If a factory part was removed, put it back and check again. If the pistol still fails with factory parts, something was damaged or reassembled wrong, and it goes to a gunsmith or back to the maker. A trigger job is not finished until every step on this page passes; parts are cheap and a pistol that fires when dropped is not.
The parts behind each check are explained in how a Glock trigger works, striker parts and the spring kits guide. Browse trigger parts and gauges; both ship to your door.
General information, not legal advice. Current as of September 2026. Laws change; check the official source before you act.
