Glock 19C
Glock 19C is manufactured in this unchanged form for a number of years and there is hardly anything to be improved at all. However, it would not be Glock if they did not manage to find at least a little room for a minor improvement. The innovated Glock 19C is fitted with a machined groove on the barrel at the top of the chamber.
At first glance, you will not even notice it. At second glance, you may see a change in the shape of the otherwise flat top of the slide, and from the design point of view, the change is for the better. It makes the pistol look more interesting and also by removing a little material the pistol lost about 1.5 grams in weight, which is of course meant as a joke. The reason behind this design change was an occasional contact of the front portion of the barrel with the slide in the area between the gas vent holes. Nothing substantial, but why not improve something that we know may be better. This is exactly the attitude of Glock. Another person may just write it off, but not Glock. They realize very well that the proverbial butterfly effect can have real consequences...