That is the magazine. Of course there are clips for .45acp too. The 1917 revolvers used half moon clips to hold the rounds. There are also 1/3 moon and full moon clips. Also some of the latter S&W model 25's took half moon clips.
Although I now understand what you are saying, I don't quite agree.
Although a clip can be a device for charging the magazine of a weapon (stripper clips), it is also a magazine from which cartridges directly feed into the chamber. Your reference to full, half, partial moon clips for pop out or break apart revolver cylinders applies to the latter, yet it also applies to a removable feeder magazine.
It would be most accurate to say that the device in question is a clip AND a removable magazine. To be super technical, it is a clip until inserted, upon which it becomes the magazine.
In such cases of user preferred terminology, you have to at some point concede to the common vernacular. But you do as you wish, you might just be a trend setter.
Clips are defined as having no moving parts unlike a magazine with a spring. Not many "clips" in use with modern arms contrary to the wide spread use of the word.