When you're building a computer, a lot of thought goes into the kind of case you're going to use for your brand new PC. Similarly, a lot of thought goes into designing these cases. Fractal Design's Josh Smith says that a reviewer recently commented on the thickness of the panels used in the company's Define XL case, because this case has super-thick panels.
Smith wanted to find a way to put a real world spin on the thickness of the Define XL's panels. After all, a measurement is just a number (or a 'boring number' as Smith says). The answer they came up with was guns. Specifically, they decided a 12-gauge shotgun was ideal for proving the durability of the Define XL's panels.
Source: Toms Hardware