I took a stock, brand new, full durability AKM and a roughly 1/2 durability (60 exactly) AKM into my firing range. I fired 3,000 rounds of BP through each gun. The 100% AKM jammed a total of 4 times. The 60% AKM jammed only once. Then I took the full durability AKM and modded it out, and fired another 3,000 rounds of BP with only two jams. So mods that reduce durability burn also seem to help with jamming, however lower durability guns will still jam even less than that.
Did these tests twice each with the same results. After a grand total of 18,000 rounds of BP, I got bored. But at least from this limited testing, full durability guns (or at least AKMs) actually do jam more.
Has anyone else tested other guns and ammo types so we can see if this is consistent across all weapons?