1. Taurus 94 .22lr Revolver - cylinder would bind up, effectively jamming it.
2. Olympic Arms K9GL Carbine - every type of malfunction in the book despite 4 trips to the gunsmith and 1 back to Olympic Arms. A client was shooting it and it almost blew up on him. I sold it to a gunstore who said they would fix it and resell it. It sold and then was back on their shelves 2weeks later.
3. Mossberg 500 Home Security .410 Shotgun - would not work with .410 handgun rounds(although it should have) and then would not work with regular .410 shotgun loads(pump action would seize up).
Browning Hi Power, CZ SP01 Shadow Custom Target
CZ 75B, CZ 75B SA, CZ 85 Combat, S&W 686+
Remington 870, S&W M&P15 Sport