1911 question: Hypothetical Sear Failure 70 vs 80

[Mossy Man]

If somehow your hammer or sear engagement failed, allowing the hammer to fall, could a 70s series fire?

Similarly, would the FPS in the 80s series prevent firing in this scenario?

[Bill Steele]

Possible yes, likely no.

You have to pull the trigger to disengage the firing pin block on the Series 80.

[Bob Hostetter]

A sear/hammer failure where the hammer is released to move forward, the hammer is caught by the half cock notch preventing it from striking the firing pin. With the addition of the Series 80's device the firing pin is also blocked from moving forward unless the trigger is depressed.

The half cock notch is protection from hammer/sear failure, the series 80 parts are for protection from dropping the gun on the muzzle and having the firing pin bounce forward striking the primer.

[dfletcher]

Hoping to get my hammer designs correct -

The Series 70 has a sharply angled "half cock" notch while the "Series 80" has a neutral angled shelf much further down than the half cock notch. I suppose the theory behind each is that if the hammer slips the sear engagement the hammer will be caught short of striking the firing pin. It's true the Series 80 locks the firing pin in place, since it's actuated by the thumb safety were the slip to occur the FP block would remain in place.

IIRC the "half cock" notch of the Series 70 was high enough on the hammer that were it to slip/break there's enough energy to fire the pistol ..... maybe.

I suppose the Series 80 is the safer arrangement. I don't like it, makes the trigger pull more of a PITA to improve. My Defender carries the Series 70 parts and FP safety filler.

[AeroEngi]

I've always wondered about this. Thanks for asking OP!

[Mossy Man]

So for an 80s series to fire without pulling the trigger, the following would have to fail:

1. Complete failure of the sear
2. Failure of the half cock
3. Failure of the Firing pin block

would the thumb safety prevent the hammer from falling should the sear completely fail?

[Bob Hostetter]

correct

[AeroEngi]

So for an 80s series to fire without pulling the trigger, the following would have to fail:

1. Complete failure of the sear
2. Failure of the half cock
3. Failure of the Firing pin block

would the thumb safety prevent the hammer from falling should the sear completely fail?

To answer your last question, no. The thumb safety is designed to block the sear from moving. If the sear completely fails, the thumb safety would not be able to prevent the hammer from hitting the firing pin.

[dfletcher]

So for an 80s series to fire without pulling the trigger, the following would have to fail:

1. Complete failure of the sear
2. Failure of the half cock
3. Failure of the Firing pin block

would the thumb safety prevent the hammer from falling should the sear completely fail?

The thumb safety works by camming against & behind the bottom of the sear - in effect, prevents the sear from pivoting forward. If the sear failed above the pivot point, or if the full cock notch failed I'd expect the thumb safety and probably the bottom half of the sear to stay in place. But I'd still expect the hammer to fall.

I suppose fully considered if the sear itself fails there's no sear left to catch on the half cock notch.

[Mossy Man]

At that point on a 70 series, there's nothing left to prevent firing

And the 80 series has a chance the firing pin block will stop it?

[dfletcher]

At that point on a 70 series, there's nothing left to prevent firing

And the 80 series has a chance the firing pin block will stop it?

In theory. But there's not alot of room in there, you'd have to wonder where the broken parts go to - they're not exactly going to fall out of the pistol. I've not heard of a sear or proper sear notch failing and as a result the pistol firing. I suppose anything's possible.

[Bob Hostetter]

I have worked in the industry for a lot years and worked on 100's of 1911's as a pistolsmith and/or a parts manufacturer. I have never seen a sear completely fail in a manner that would allow the hammer to fall and strike the firing pin. I have seen them lose their sear edge where they engage the hammer hooks allowing the hammer to fall to half cock. Not saying it's impossible but it's right up there with winning the lottery or getting hit by lightening ... twice.

[Mossy Man]

That's comforting. I carry my Glocks with confidence since they're only half cocked, and won't fire unless the trigger is pulled. Just trying to understand the internal mechanics of my 1911.

Thanks for the responses.

[dfletcher]

That's comforting. I carry my Glocks with confidence since they're only half cocked, and won't fire unless the trigger is pulled. Just trying to understand the internal mechanics of my 1911.

Thanks for the responses.

I guess it comes down to what one is used to. I bought a Kahr Mk9 for my nonres CCWs, just couldn't bring myself to carry it with a round in the chamber. I know how it works, but that it was "half cocked" & the pistol has no safety bugged the heck out of me. I've no issue carrying a 1911 "Condition One" because that's what I'm used to. I recall working in a liquor store about 35 years back, getting into a fight when someone tried to steal a bottle. When the guy knocked me on my butt my shirt came up showing a Detonics ready to go. Took a minute to figure out why the guy's eyes got wide and he skipped out quick.