I think it is what they call a drop block breach.
It’s OK, it just looks like that.
The rear of any gun barrel is called the "breech." It is where the ammunition is loaded. Minor spelling correction. (Also what a rear-presentation baby birth is called.)
Furthermore, my impression is that a drop-breech or falling-block firearm is a quite different loading mechanism, not like this type of autoloader. In this pistol, the rear of the barrel is connected with a link to the frame. The simultaneous rearward travel for a short distance causes the rear of the barrel to drop just enough so as not to hinder further rearward travel of the slide, ejecting the brass, then a bit farther yet to permit the spring-loaded next round to enter the chamber.
The action stays open (as in the photo) after the last round is fired, so that changing the magazine will permit the new top round to be autoloaded.
See the very nice animated drawing in Post #27 above and follow the action of auto-loading.
FYI