The 1911 cannot be safely carried with a round in the chamber hammer on it I dont care if its inertia driven or not.
Drop tests indicate differently, but then again there may be extreme circumstances not covered by drop tests, perhaps some may carry while working as a high steel rigger or rodeo bull rider.
In anycase drop tests indicate that a 1911 with hammer down is no more likely to go off than the same pistol cocked and locked.
Its meant to be carried Condition 1 or Condition 3.
We were discussing the designer's intention (no thumb safety on the 1910 prototype) and instruction manuals, the army intended for cocked and locked carry if combat was imminent, and only then in the issue flap holster.
Of course any time after the gun has been drawn and cocked or cocked and fired, the thumb safety is very valuable if you then have to move about or are subject to unexpected blows or startling events such as gunfire or explosions, etc.
I have read an account of a 1911 carried cocked and locked in a thumb break holster being disabled by a hard knock on the cocked hammer. It did not go off, but then again it could not be fired at all until after a very expensive stay at a gunsmith shop.
And as for AD its the users fault doesnt matter if its SA or DA.
If the pistol is in A-1 working condition thats usually true.
If the pistol has a worn out sear or other mechanical defect due to substandard materials or heat treatment, then it may well be the fault of the manufacturer.
There have been recalls of Colt manufactured 1911 pistols due to poorly heat treated safety levers, with the warning that these can cause an accidental discharge.
Firing pins don't grow longer with use, so if the floating pin is long enough to contact a primer with hammer down, its the manufacturers fault.
If a primer ignites with only a very light ding or vibration of a safety strap snap being applied, then its the cartridge manufacturers fault, and it could just as easily have gone off when chambering a round.
The Remington Rand is one of the best WW2 era clones of the 1911, but the early production pistols don't pass the parts interchangability tests. Some of these require careful handfitting of replacement parts to ensure safe operation.
But really its all a matter of what you feel comfortable with.
I don't feel comfortable in carrying cocked and locked because I've run across an autoloader that could go off the moment the safety was disengaged without a finger on the trigger. Not a 1911, but it affected how I feel about autoloaders.
At least twice I've had .22 rifles go off when the safety was disengaged, not handguns, but these also effect how I feel about trusting the safeties of cocked firearms.
and a PPS
Only reason I came back so soon was I just found that on my FN 1922 the thumb safety and the magazine safety only operate if the grip safety works.
If the upper engagement surface of the grip safety is broken or worn down then neithter the thumb safety nor the magazine safety will prevent the pistol from being fired.
Figured other FN 1910 or 1922 owners should be told of this.