Just my opinion.
I think with virgin brass the cases would not fail.
When shooting factory reloads,you had no opportunity to inspect/reject brass.
You have no idea how bulged that brass may have been.
When an unsupported case bulges,some areas may be gently stretched,but some areas are abruptly offset.They are very nearly sheared.That material is compromised.
There are dies that can reform the brass back to looking OK ,but they cannot restore the material integrity.
I'd send pics to the manufacturer .I'd offer to sell the remaining ammo back to him.IMO,he would be crazy to not take you up on it. Once you have documented and informed him of the issue,the refund is cheap compared to his exposure.
If the manufacturer has integrity,he will want to contain and recover any quality issues.It gets studied,they learn and hopefully recall bad lots.
FWIW,IMO,its poor economy to continue to shoot failure prone ammo.A 40 is fairly high pressure and even a minor trip to the emergency room will cost more than 1000 rounds.Besides,stuff like that makes me jumpy and distracted. Its hard to shoot well.
There are a few brands,such as BlackHills,that I would trust for reman ammo,but no,not just anything on a gunshow table.
I don't have a 40,but WW white box walmart hardball is quite affordable compared to reman at least in 45 and 9mm.
That's how I see it,anyway.