The Luger used in Reeves' death was a commercial .30 calibre, virtually identical to the 9mm P08 made famous by the German military.
Unlike its replacement (the Walther P38), the Luger has an internal firing mechanism, not an exposed hammer.
A cocked hammer would have been very identifiable to a man who served in the US miliary, as had Reeves. You cannot tell if the Luger is ready to fire though.
The Walther has an indicator pin that protrudes, inidicating there is a (live) round in the chamber. Not so with the Luger.
Therefore, one cannot tell if the pistol is either loaded or ready to fire.
The only inidactor is the safety selector switch, located above where the web of the thumb is when held in the right hand.
If the Luger were in Reeves' nightstand and he were sitting on the side of the bed, he might easily pull open the drawer with his right hand and lift away the ready-to-fire Luger with his left.
If the Luger were in the drawer, pointed away from the bed, as it might be for him to draw it with his right hand were an intruder to be confronted, then lifting it up to gain access to something else in the drawer would be done with his left hand.
Swining the Luger up (it's a heavy piece) to hold it better, places the back of the handle in the inside of the finger/palm junction and the thumb inside the trigger guard.
I am unclear if the .30, commerically-manufactured Lugers had "grip safeties," but even so, the weight of the firearm being supported in the hand, muzzle upward, or at a 45 degree angle, would be enough to compress it and obviate the last saftey device.
What I am saying is: being a little bit groggy from the alcohol, Reeves mishandled a live firearm, flipping it up and, thereby, pointing it at himself from a distance of aproximately 20 inches (a reasonable armlength for a man of his stature in the positon I describe) and touching off a round, shooting himself in the head.
The spent casing on Lugers ejects the right and slightly forward. This means the case is spat out past his left shoulder (remember, it is his left hand holding the Luger in my scenario), landing on the bed behind him.
Reeves drops the handgun in the exact location that is consistent with this theory and falls backwards on top of the shell casing.
I grant you there are any number of other theories --some more plausible than others-- but this one is straightward and is consistent with the physical evidence.
I submit: George Reeves died as a result of a combinaitnon of the two folloiwng factors:
1 - Poor firearms' storage.
The gun was put away with a live round in the chamber (which means the firing mechanism is cocked) and the safety (which could not be seen when pointed away from the bed), and
2 - Mishandling a firearm.
He carelessly picked up a loaded gun after he had been drinking.
This theory may not be as interesting or exotic as others, but is all-to-familar. This means Reeves wasn't the victim of foul pay, nor was he despondent. He was a guy who made a mistake.