Back in the early part of the mid 1970's I had a small commercial reloading business. I have to agree either the reloaded was just plain sloppy or is trying to milk that brass for as many reloads as he can get away with.
The sooty cases and yellow residue are definitely signs of underloaded crtridge. I'm guessing with some confidence that the powder used was one of the ball type, probably W321 or HP38. (Different lots of the same powder.) The large amount of split necks is probably brass loaded too many times with the necks belled a bit too much and possibly too mich crimp. The anaolgy of bending the paper clip being spot on. As the reloader is loading lots of ammo at a time, I'm thiking progressive press wit an automatic case feeder. He wouldnt have a chance to inspect anyhing until he final product and considering the large quantity of procuct, he didn't bother except possibly on a sporadic basis.
I only load two cartidges on a progressive, 9MM and .45 ACP. It's a Dillon 500B and as I have to insert each case into the machine, at least each case get some kind of inspection.
Most of my shooting is .38 Spl. with a 148 gr. wadcutter I cast myself. I use 3.1 gr. of either Bullseye (rarely anymore) or 3.1 gr. of W231. I once bought a couple of boxes of commercial .38 Spl. target loads Federal and Winchester) and to my shock, my loads outshot both brands
and the Federal ammo had long longitudinal splits almost the full length of the brass case. My last run was 1,88 rounds on a Rockchucker single stage press. I've got to sit down and cast up more bullets a I'm almost done with the last run.
Paul B.