TexasCHLforum.com

One of the issues with some .40 S&W handguns is a design issue. There are some manufacturers who originally started with a 9mm design. They then extended the same design into a .40 S&W package, which basically means enlarging the bore while keeping the same barrel O.D. in the same size frame. I've "heard" the .40 S&W model is thus less robust than the same gun in a 9mm model.

As the .40 S&W caliber reached critical mass in the market, apparently some manufacturers changed their design process to first size the handgun to have a robust safety margin for .40 S&W, and then downsized the .40 S&W design to make the 9mm version. Although the 9mm version is still more robust than .40 S&W dies due to the barrel size, at least the design baseline is provides a robust safety factor for the .40 S&W.

As far as .40 Glock Ka-BOOMs specifically, that is directly related to the unsupported chamber. It is such a well-known issue that there are products now sold by reloading equipment manufacturers to directly address removing the case bulge from .40 S&W Glock-fired cases.