there are several parts to the issue. The 40 S&W was designed by S&W and Winchester. That's who submitted the specs for the cartridge to SAAMI. The original cartridge cases were thinner than current cases. All American ammunition makers made cases that were all about the same thickness. Federal cases were 'weakest" or softest. A lot of pistol companies had a hard time getting the cartridge to feed. This lead to large chambers and low angled feed ramps (that left more unsupported). federal had the most case failures and recalled their 40 S&W ammunition. They replaced it with ammunition that had thicker cases. Due to safety concerns, all of the other big American ammunition companies followed with thicker cases. Bullet setback was also more common with the early thinner cases.
Fired cases from the early 40 S&W Glocks can look, "ugly" due to large chambers and low feed ramps. Sometimes they don't look reloadable at all, depending on the case and the chamber. The newer 40 S&W Glocks have more vertical feed ramps that give more case support above the ramp. My newer Glock barrel makes the rounds,"jump" into the chamber and doesn't feed very smoothly. My early Glock barrel would have the rounds glide smoothly into the chamber. Chamber diameter also affects case expansion and life.
Current 40 S&W cases are about as thick as 357 Sig cases. Even though the companies other than Federal didn't recall their 40 S&W ammunition due to weak cases and case failures, they all switched to thicker cases after Federal first made the change.
Despite some media reports, there were no AK-47s involved in the incident