1911 Safety Information

[mwpslp]

I was wondering, if the sear were to fail on a 1911 style pistol being carried "cocked and locked" would the hammer fall? Would the thumb safety have to be disengaged for this to happen? Would the grip safety have to be engaged for this to happen? I know some guns have a firing pin block while others do not. How would this come into play, if at all, in this situation?

I know these are pretty basic questions to some but I just want to make sure I am understanding the inner workings properly. Thanks in advance for the help in understanding.

 

[jungle]

If the sear nose breaks in a cocked and locked 1911, the thumb safety will prevent hammer fall if engaged due to the safety/hammer relationship.
In a standard 1911 the grip safety only blocks the trigger.
In pistols with firing pin safeties, the firing pin is blocked from movement until a) in series '80 Colts the trigger is pulled through or b) Kimbers,S&Ws the grip safety is depressed.
If the sear breaks during firing, the result will be hammer following slide and the pistol will cease fire in most cases.
Sear or hammer notch breakage is quite rare, there is a lot of metal there.