G'Day Fella's,

NitroX, this can be a common occurrence on semi-auto pistols, if the operator does'nt create enough resistance. This is commonly referred to as a "Limp Wristed Hold".
What happens is, if the pistols doesn't receive sufficient resistance from the operator, it will act like a single shot.
The pistol needs to be held with a strong hold and enough resistance thru the hand, wrist and elbow, to create enough resistance to hold the pistols frame in place, to allow or make the slide unlock and move all the way to the rear.
If the slide doesn't travel all the way to the rear, it may not have enough return spring pressure and inertia, to travel back forward with enough force, to strip another cartridge from the magazine and chamber it (as can be seen with the Desert Eagle, in this video).
In my experience, the bigger the cartridge is, the more important the above is for reliable functioning.
Thats probably why I refer to 9mm', as Rat Gun's, as this is generally not an issue with them.

Hope that helps

Avagreatweekendeh!
Homer