[JesseA422]

shortly after building a bbc last year for my 77, i had a no start condition (cranked fine), and chased it to bad contacts in the ignition switch. i replaced it with a unit from autozone, and i didnt have an issue for the past year.
2 weeks ago i once again had a no start condition. it seemed like i was once again having low voltage to the distributor (HEI, resistor removed from distributor wire). i once again replaced the ignition switch with another unit, this time from napa. after replacement, truck fired no problem for the past 2 weeks.
this morning i went to drive my truck to work and once again, cranks fine but no start. truck starts fine if i run a jumper straight from battery to distributor batt terminal. im going to replace the switch again soon.

is this a seemingly bad string of ignition switches, or is there some other issue at play making these switches go bad?