A speed reload (also known as a "combat reload") is the action of reloading a weapon in a very short amount of time by ejecting the currently loaded magazine with one hand, and drawing as well as loading fresh magazine with the other hand. This is quite similar to a regular reload of a weapon, but when well performed can have a large time advantage. The tactical advantage here is lost with closed bolt weapons that do not have a round in the chamber, as the gun will then require cocking with the new magazine inserted to chamber the new rounds. This does not apply to open bolt weapons, as they do not require charging. A speed reload is often thought to be more or less the opposite of a tactical reload.
Advantages and Disadvantages
The main advantage of a speed reload is quite simply speed. If done right, it should take anywhere from five to ten seconds. The main disadvantages of a speed reload are that if there are rounds left in your ejected magazine, you will lose them, and it is much louder than a tactical reload.