1911 Thumb Safety locking the hammer

[battlecry]

I want to swap the 1911 thumb safety from my Wiley Clapp LW Commander to my Colt Series 80 1991. It passes the safety tests on the 1991, including the click test. When overrotating the hammer (a Harrison retro spur hammer) past full cock, it turns smoothly until it kisses the GS tang.

Now here's the odd part, with the thumb safety on, the hammer is locked, it won't move back. Using external pins on the frame, the hammer can overrotate past full cock and there is clearance with the body of the sear. Assembled without the GS, I see that the cam from the thumb safety rotates and locks the sear, but it also rotates into the hammer cutout and blocks it.

I thought the thumb safety had to cam in place to lock the sear from rotating even a small amount (the click test) and that was what locked the hammer. This one seems to also physically block the hammer by engaging the hammer cutout.

My other 1911s can rotate the hammer slightly past full cock with the thumb safety on and they pass the thumb safety tests. So what confuses me is this, if the other hammer/sear/safety combos can rotate slightly past full cock, does it means that the safety allows the sear to have some wiggle room so the hammer flat past the hooks can overrotate it a little? My Gold Cup Trophy has an EGW safety and the WC LW Commander has a Harrison, and the sear engagements are solid but they do not engage the hammer cutout to block it like the 1911 mil pattern safety from the WC Commander. Maybe the hammer flats do not push on the sear much when rotating it a small amount.

I think my firearms are ok and they just operate differently because of the different pattern parts and this is just a newbie observation, but I'd like to hear if anybody have any comments or cautions I should be on the lookout for. Thanks.

 

[Drail]

Um, you cannot "swap" thumb safeties (perhaps I misread your post). They are fitted to the individual frame and sear and hammer, and they're all different. A 1911 is not an AR. Nothing will simply "drop in" and function properly, most especially thumb safeties. If you have "swapped" thumb safeties between two pistols you need to put them back as they were installed. If you want to learn how a 1911 functions buy Kuhnhausen's 1911 Shop Manual (Vol. 1). Read it 4 or 5 times. It's a lot of material but it will save you a lot of money (and headaches) if you are going to do your own work.

 

[battlecry]

Understand, and thank you Drail. The safeties have been fitted and all pass the safety tests. They all block the sears solidly. The mil pattern safety was the first I've seen that strongly blocks the hammer using the cam in the hammer cutout as well as the sear. I expect hammer rotation past full cock with the thumb safety off to respond to recoil and to engage the GS with the hammer spur. I did not see anything in Kuhnhausen about the hammer rotation past full cock with the thumb safety on, which is possible on my GC and Commander. Does the hammer flat under the hooks stress the safety-locked sear when this happens? It appears to me there has to be some wiggle room in the hammer/sear/safety geometry to permit the rotation. (?)

 

[brickeyee]

The fitting of a thumb safety is the last chance to take the tolerances out of the frame, pins, hammer, sear, etc.

 

[battlecry]

Drail/brickeyee do your thumb safeties allow a slight rearward movement of the hammer past full cock when engaged?

 

[Drail]

Yes, all 1911s will allow the hammer to be overcocked. It is overcocked every time the slide resets the hammer. That has nothing to do with the thumb safety (unless it is bearing on the hammer somehow). The thumb safety only blocks sear movement. If the hammer is overcocked it will reset forward against the sear nose. The sear spring holds the sear against the hammer. The thumb safety simply keeps the sear nose into the hooks. If your hammer is not free to overcock (safety on or off) then something is blocking it (most probably not the sear) What do you mean by "the safeties have been fitted?" "Fitting" means file/stoning an oversized safety to fit your gun. Did you stone them?

 

[rcmodel]

There is nothing on the safety that should be close enough to the hammer to prevent it from over-cocking with the safety on.
Thats the way they are supposed to work.

See this link.
http://www.thehighroad.org/showthread.php?t=231096

Again.
If I were you, and would put the safeties back in the guns they came out of.

rc

 

[battlecry]

Yes, Drail, with stones Brownell's and care and patience learned from years of 1911Tuner's posts. The EGW and Harrison thumb safeties block the sear and thus the lock the hammer on their respective guns. The Colt 1911 mil pattern locks the sear but also physically blocks the hammer using the cam and the hammer cutout, so the hammer cannot be overcocked with the safety on. So you see, I have one firearm that behaves differently from the other two, and since I have not worked with a mil pattern safety before I just noticed the difference.

If you have a 1911 with a Colt teardrop safety, can you tell me if you can rotate the hammer backwards a bit past full cock with the thumb safety on?

Thanks

 

[JRH6856]

Why don't you post some pictures of the safeties in question? I would like to see a side by side comparison of the sear blocks on the safeties taken from different directions.

 

[battlecry]

Thanks, RC. If I were to overlay my 1991 on the top picture, you would see the safety cam part, where the #1 arrow points to, blocks the cutout in the hammer when it is engaged. I can file the back of the cam to unblock the hammer and leave all safety action to the front part that blocks the sear. I do not think I want to do that. I'd like to understand if I'm stressing the blocked sear on my other firearms if the hammers go past full cock with the safety on.

 

[battlecry]

JRH, sorry I took pictures but realized I need to host them somewhere on the net and I don't have a place to host/link to.

 

[JRH6856]

You may like having the hammer locked by the WC safety, but such "hammer locking" indicates to me that the safety may not be properly fitted and may actually be unsafe as early contact with the hammer by the safety may prevent the safety from fully engaging and locking the sear as designed. OTOH, the designer of the WC safety may have thought blocking the hammer to be a an additional safety feature. If so. it would have to be precisely fitted to the existing tolerances on that particular gun. Switching the safety to a different gun might appear to produce the same locking conditon, but not having been fit to the tolerances of that particular gun, the actual condition may or may not be safe.

(You can host pics here. Just go to the advances editor, click on the paperclip and upload them as attachments.)

 

[brickeyee]

Over cocking is NOT a problem in the 1911 design.
The hammer is going to hit the grip safety under the impact of the recoiling slide.

 

[battlecry]

JRH, thank you for the thoughtful comments. I'd be concerned with the safety also if it were not blocking the sear, but it does. The fact that it also blocks the hammer from overrotating back, past full cock, is probably a quirk of the part patterns and tolerances.

I swapped the original Colt teardrop safety back in the GC and I can rotate the hammer slightly past full cock with the thumb safety on. When fitting the safeties, I paid attention to blocking the sear and preventing the hammer from going forward. Never thought the hammer could (or should) be moved back. Learned a new one.

Thank you for the tip about the attachments. Will use it in the future.

Regards,

Roberto

 

[BBBBill]

There have been lots of variations on sear and hammer design by various makers over the last few years. Most have to do with the hammer hook/flat location relative to the pivot hole, hook profile, spur design, weight removal in the sear and hammer, etc. All in a quest to improve the geometry of the parts so provide a great trigger pull as easily and safely as possible with durability for long life. The one constant is blocking the sear from any movement with a properly fit thumb safety. Hammer over cock while the safety is engaged is totally irrelevant. If the sear is properly blocked, the hammer will come back to rest on the sear nose. The slide cannot move (more than a few thousandths) with the safety engaged, so the only thing that could over cock the hammer is your thumb.

 

[rcmodel]

I'd like to understand if I'm stressing the blocked sear on my other firearms if the hammers go past full cock with the safety on.

No, you are not in the slightest.
That's the way they are supposed to work.

As stated above, the hammer 'should' be able to be over-cocked with the safety on.
For clearing a grain of sand or dirt binding the safety stud to the hammer, etc.


If the sear isn't fully engaged in the hammer notch for whatever reason?
Or it's jammed with sand?
It will be cleared after over-cocking and letting it back down to full sear reset in the hammer notch.

I'm not sure I would trust a safety that didn't allow over-cocking for a full sear re-set if necessary!!!

rc

 

[battlecry]

Thank you all. Learned some more again today. Regards, Roberto

 

[Jim K]

If specs are not held, the end of the safety can interfere with the hammer strut. Since the strut has to move forward when the hammer is cocked or overcocked, the safety can keep it from moving, blocking the hammer.

Jim