Can't speak for all 1911s, but I can engage the safety on my 938 without the hammer back.
Simple answer here - the 938 isn't a 1911. It's a hammer fired Sig design, based on their P238, which is based on a Colt Mustang, which is based on a 1911... The P238/938 is NOT a miniature 1911 clone, but rather it is loosely based on the 1911.
Certain people have complained about the 1911 design for as long as it has been around, such you can't set it to safe with the hammer down. So as the design evolved from one model to the next, new features were added to address those complaints.
Even though we call the same Cooper Carry Conditions for basically all hammer fired SA pistols, they're not all the same, and the P238/938 isn't a 1911.
One distinct advantage, is the lack of a physical slide block in the safety. In a 1911, the shooter must deactivate the safety to clear the chamber, which has been a common complaint for many shooters over the years - why force me to make the pistol "less safe" by deactivating the safety when I'm trying to make it "more safe" by unloading it? Comparatively, in a P238/938 in Condition 1, the shooter can empty the chamber while leaving the safety activated. In Condition 2 (loaded chamber, hammer down), the safety must be deactivated to manipulate the slide, adding increased risk of administrative ND's.
When the hammer is cocked in a P238/938, it disconnects the trigger from the hammer. When the hammer is down, the 238/938 safety blocks the hammer from cocking past half cock, which subsequently blocks the slide from opening fully. HOWEVER, if you pull the trigger with the safety on and the hammer at half cock, it will fall as if it were fired, so it's not really a true half cock notch, but rather is more like a half cock sear, AND in pulling the trigger, you will defeat the firing pin block safety so it WILL hit the firing pin... It won't hit it with full force, so it won't fire, but it's NOT a secure half cock notch. So personally, I'm not really certain why they have a half cock position at all. The P238/938 also use an inertial firing pin, so when the hammer is fully down, the pin is NOT touching the primer. Hitting the hammer spur when the hammer is down will be no more likely to fire than if the hammer were locked back by the safety.
Sig's recommendation are ONLY these:
1) Condition 1 carry - hammer back, round chambered, safety on
2) Condition 3 carry (Modified) - hammer down, empty chamber, safety on (which is foolish and unnecessary)
HOWEVER - If you are willing to go against common sense AND against Sig's official instruction: AND willing to assume increased risk of administrative ND's:
Condition 2 carry is safe in a Sig P238/938. As foolish and unnecessary as it might be, the Sig P238/938 can be carried safely with a round in the chamber, hammer down, and safety on. A) With the safety on, the hammer will not draw back past half cock, and it cannot fall from there with enough force to ignite a primer. B) With the inertial firing pin and firing pin block (redundant in Condition 2), hitting the hammer cannot ignite a primer, any moreso than dropping the pistol in Condition 1. Sig designed in plenty of safeties into their pistol to prevent injury of fools who do foolish things, and Condition 2 carry is on that list. Again - if you carry in Condition 2, you'll have to deactivate the safety to unload the pistol, increasing your risk of administrative ND's.
