Quite often there's a bug with the Deagle's magazine that won't change when holding the R key, I like to use two spares magazines besides the one in the gun and usually the one inside the gun when I start playing won't respond to the R command, I have to drag it out with my mouse and replace it with another magazine and the other 2 magazines will respond normally, but when I put the first magazine back the bug appears again.
In addition, there's another bug with the deagle, when climbing a ladder with the Deagle in hand, the pistol dissapears but a single bullet reamins "floating" around my right hand.