Blowing up an engine is never good. There are literally hundreds of possible failure points in an engine that range from component failures to operator error, or in the case of the pistons shown in this video, assembly error. The guys at MAHLE talk about pint bore circle failure in this video and they go into some great detail about the hows and whys of investigating failed parts after and engine comes unglued.
MAHLE uses circlips to retain the wrist pins in many of their piston applications and when they are installed correctly they are designed to function for as long as the pistons and rods are used in your engine. Like all of the elements in assembling an engine, the actual work of installing the clips may be basic but the execution is absolutely critical. Seating the clips correctly and handling them the right way can determine the lifespan of your engine. That lifespan can range from minutes to decades and according to the engineer in the video, when the Mahle guys get parts back to analyze and they hear that an engine failed quickly after initial start up, circlip issues are usually what they find.
If you are going to be screwing an engine together this winter, take heed of this video. MAHLE pistons are among the best in the world and they will do what you need them to do for a long, long time if they are handled and assembled correctly. Make sure your pistons don’t end up looking like this!