De-Cock a 1911?
First...
It's a gun. It's NOT safe!
Second...If the chamber is hot, the hammer should be at full cock, and either readied to fire or the safety engaged. It is no less safe in condition one than in condition two.
That bein' said, proceed to...
Back in the bad ol' days when the 1911 was still Uncle Sugar's
issue sidearm, the MPs and SPs who were returning their weapons to the armory at the end of their daily/nightly tour, the clearing procedure was thus:
Drop the magazine first. Not second, not later...First.
Rack the slide twice, and visually inspect the chamber to insure that a live round didn't escape your notice.
Point the pistol at a 55-gallon drum that was about 2/3rds full of sand and pull the trigger.
Want to take a guess at how many hits a month that drum averaged?
The 1911 wasn't meant to be de-cocked...though many people have done it
successfully over the years without incident...yours truly included....but it's an inherently dangerous practice, and not recommended without dry-practice..about 500 times without losing control of the hammer should do it.
One slip, and you need to start over.
When you move on to lowering the hammer on a live round, be sure to have an adequate bullet trap to point the gun toward. A 2-foot thick stack of dry newspapers will do. Be sure and point the gun straight down into the stack, and expect that if the hammer gets away from you, the slide will
very likely break your thumb unless you employ the weak-hand pinch method.
Reach over the top of the slide with your weak hand and grasp the hammer firmly between thumb and index finger. Push the hammer past full-cock as you depress the grip safety...not AFTER. When you're confident that you truly have control of the hammer, pull the trigger and lower the hammer. Note that this method makes the stack of newspapers very difficult to point the gun straight down into, so it's highly adviseable to
perform this outdoors or in front of a suitable vertical bullet trap such as the type found on indoor ranges.
Now comes the question...
Why would you want to lower the hammer on a hot chamber? The pistol can remain cocked and locked for over 50 years without weakening the mainspring to the degree that would cause misfires. Just curious...