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Thumb safety

3K views 21 replies 12 participants last post by  Albroswift 
#1 ·
Should the thumb safety be able to move/raise up at all when hammer down? Fitting a WC and hadn't noticed this before. Went back and checked some of my other 1911s, some move very little some move more. This one actually moved enough to block slide, but pretty square slide stop corner where others are eased. Eased this one just a little, doesn't interfere any more (but still moves up obviously), should have taken a picture first, sorry.

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#3 ·
OK, Thanks.
First one I had that actually interfered, really trying to get things right.
For me, seems like fitting the little things are turning out to take way more toll on my skill and patience then the big things.
 
#7 ·
Looks like the detent is shallow, as was mine, so deepening it will make the safety's action feel more positive.
 
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#8 ·
@BBBBill yes, rounded it a little. Still have the detent. Going to replace with a parkerized ambi, thought I would like the ss bling but no.
@RickB copy that, spent a lot of time on it and have it feeling nice and snappy, but starting over per above. Thanks for the tips.
 
#10 ·
I like to use a small burr and ramp the detent so it looks like an upside down water drop. I do that also on the detent of the blade of liner lock knife blade so it goes in and out smoother.

LOG
 
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#13 ·
Carefully examine some unaltered or otherwise properly fit safeties with a magnifying glass if it helps you see. Specifically look closely at the front where the detent pin rides. Note what RickB and log man said above. Search out more threads here on fitting thumb safeties. You'll get there.
 
#14 ·
#15 ·
A couple of pics that may be of some use.

Here's the upside down water drop shaped detent that log man references. The top edge is responsible for stopping the downward movement of the safety. The bottom edge determines how much effort is needed to push the safety upward into the on-safe position. I too use a small, round, diamond burr to modify the shape of this detent to give me the feel I want.


Here are a couple of critical fitting points. The shape and depth of "A" determine how much effort is required to push the safety down into the off-safe position. "B" is the engagement surface with the sear. Note the worn away blue indicating solid physical contact between the two parts.
 
#17 ·
What works for me. This has been edited to be more complete/concise. I probably still forgot something. Warning - This is MY WAY. Pros may have a BETTER way.
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First make sure that you are through fitting your sear/disconnector/hammer before beginning to fit the thumb safety. Any "trigger job" work done after thumb safety fitting may render the thumb safety unsafe. Fitting the thumb safety to the sear should be the very last thing you do.

The safety must be fit (as needed) to the frame, the slide, and the safety detent plunger as well as the sear.

First, examine your safety to insure that the pin is straight and square to the body of the safety. I've seen some pretty bad ones come out of the package. Either straighten it or return it for one that is square to the pin/body. You may have to stone the back of the shield (flat portion that rides the outside of the frame) to eliminate any machining/casting irregularities that will prevent it lying flat and/or scratching your frame. Do not remove the radius at the root of the pin.

I also check the diameter of the pin holes in the frame and grip safety vs the pin diameter on the safety. Pin diameters I've seen vary as much as .009" (Wilson is noted for being large) and can affect the function of the grip safety at the extreme ends of the spectrum as well as cause friction drag on the thumb safety if there is not enough clearance. If the thumb safety pin drags/binds when inserted through the frame and grip safety with nothing else installed, you've got to address that up front. You can reduce the thumb safety shaft diameter or ream the frame/grip safety holes. I prefer to reduce the thumb safety shaft.

Then, strip the frame of all parts so that you can insert the thumb safety by itself and observe any interference. Insure that you remove the safety detent plunger assembly. You want no possible resistance from anything except the frame itself. Fit to frame to insure that it is seated fully and smoothly moves fully from on safe to off safe.

You may find that the notch on the underside of the safety lug is too narrow and binding on the frame window. It would be good to add the hammer and sear pins here and check again for drag/binding. I stone the tops of the pins to remove any machining artifacts that might scratch or drag on the back of the thumb safety. I like to leave them a couple thousandths proud of the frame to help prevent the TS from rubbing/scratching the frame finish. Relieve the face of the lug to widen the notch ever so slightly with a safe side needle file if needed. Remove only enough to allow the safety to clear the "window ledge" and drop all the way down. .0005" -.001" is plenty. More is too much.

The stop surface of the thumb safety lug can be too sharp and dig into the bottom of the frame's thumb safety lug window, creating an unsightly divot. That can be addressed by filing the sharp surface to spread the contact. The stop surface can also lack enough material, allowing the thumb safety to overtravel and drop too low. Some smiths use TIG or silver solder to build that up and file to desired shape to correct the depth of the stop point and provide a wider contact surface.

Then install the hammer/sear/disconnector and fit the safety to the sear to insure no (absolute zero) movement of the sear/hammer while on safe. Insure that the safety is fully blocking the sear while in the up position with the slide on. Do not fit the safety to the sear with the slide off as the safety can sometimes overtravel upwards without the slide resulting in a poor fit to the sear when fully assembled. Check fit of the safety upper blocking surface in the slide notch while on safe. Adjust fit as needed.

Then remove the hammer/sear/disconnector again, reinstall the detent plunger assembly, and fit the forward face of the safety to the detent plunger for proper "feel" when moving on and off safe.

The top front corner of the plate may need to be adjusted for clearance from the slide in the off safe position. Sometimes a file stroke or two on the forward face (where the detent is) may be needed to allow the thumb safety to rotate up into the slide notch.

Finally, blend/contour the back edge of the shield to the frame to avoid any sharp edges/discomfort and detail the exposed parts of the thumb safety to enhance appearance.
 
#22 ·
Thanks, everyone. Do-over went well. Next time I'll blow the dust off before taking pictures. Going to shoot it tomorrow and then if everything goes well maybe blend the slide at the rear.


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