IIRC Combat Magnum production began in 1955 with only one or two VIP guns leaving the factory prior to the 1955 Christmas holiday shutdown, regular shipment begins in 1956 .

The L frame 586/686 series is actually the "Distinguished Combat Magnum" and the fixed sight 581/681 is the "Distinguished Service Magnum".

IMO while moonclips aid extraction when using rimless rounds in a revolver and make for faster reloads when racing the clock in competition Im not sure there is any benefit to modify a .44 Magnum for moonclips unless you are using it in competition ,
If so the excessive recoil and muzzle flip of the 44 Mag cartridge would likely negate its use.
The advantage of Magnum rounds are their higher lethality from a well placed center mass shot with the focus on accuracy instead of volume of fire .
If there is a reasonable threat of multiple targets or a prolonged gunfight scenario requiring a higher volume of fire its time to consider a 15 shot 9mm semi auto with two spare mags,...In that scenario some believe a handgun is a tool best used to fight your way to your rifle or shotgun