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Glock Manual Thumb Safety

People always want to know why anyone would want a manual thumb safety on a Glock. Without getting into that religious war, the answer is simple. Many things besides a finger can and do pull the trigger of a handgun. I was standing beside a guy that shot himself in the buttocks and leg when his shirt tail pulled the trigger on his G17 while he was re-holstering.

At any rate, below are the picture taken while a Cominolli manual safety was installed in a G21. The Cominolli manual thumb safety seems to the only product that fills this market. It is very well designed and works very well.

These ideas are free for non-commercial use and are offered with no warranty or other claims expressed or implied. Ken Reed, 04/20/2007.

Here are the contents of the Cominolli kit.

Here is the G21 before the process starts.

Here is a close up of the affected area. A slot needs to be cut for the manual safety.

The machining jig is attached to the frame of the handgun.

The machining jig attaches with two pins through the jig into the frame and one clamp.

The end mill is inserted into the machining guide. It is extended only a small bit for the first cut.

The first cut is made about 1/16" deep, several more 1/16" deep cuts follow.

The final cut is about to be made. The end mill is turned by a Dremel tool, while the machining
guide follows the slot in the machining jig.

The trigger bar guide is installed. It slides on the extractor and in the trigger housing.

The detent pressure plate is now installed. The spring washer is behind it. Note the top hole
is larger than the botton hole, The top hole was drilled with a #52 drill, 0.064", bit to make the
on-safe position have a stronger more positive detent.

Now the safety lever is fitted and installed. The safety lever needs some material filed off to allow
the safety to just go on when the pistol trigger is forward. This is a trial and fit operation. It is best
to take off only a little metal at a time. Note the 90 degree edges on the thumb lever area. That
may need to be fixed later.

After everything is back together, this is the on-safe position.

This is the fire position. A very neat and clean installation.

The shooting grip with the safety installed is perfectly normal. The position of the safety relative
to the frame makes it very easy to grip the handgun with the strong hand thumb on top of the
safety. This is a common shooting grip for 1911 type pistols with the thumb safety in the same
location. This gives a very high grip and ensures that the safety is indeed off.

After dry firing a few hundred times it became apparent that the 90 degree edges on the thumb
lever area was not going to be comfortable. A few minutes with a file and some 440 grit
sandpaper makes the thumb lever area much more comfortable. I will paint it black again
when I have decided that is it comfortable enough.