Is the 44 magnum the most powerful handgun in the world?

Answer 1

No. Most powerful handgun can be a bit ambiguous, considering that many short barreled rifles are sold in the US as handguns, minus the buttstock.

As for purpose made and designed pistols, in the traditional sense, firing a dedicated handgun cartridge, the answer still is no. The most powerful production pistol in the world which fires a dedicated pistol cartridge is the Pfeifer Zeliska revolver. It fires a .600 Nitro cartridge. There are several other dedicated pistol cartridges which eclipse the .44 Magnum in terms of power - .454 Casull, .50 Action Express, and .500 Smith & Wesson Magnum are some of the better known ones.

Even when Clint Eastwood claimed in the movie 'Dirty Harry' that the .44 was the most powerful handgun cartridge in the world (the movie was released in 1971), he was already outdated - the .454 Casull had already been introduced in 1959.