Correlation does not imply causation. Look it up.
Notice that I didn't say that it did? Nope, you didn't. Look it up.
"Correlation does not imply causation" is commonly used concept in statistical analysis. It is phrased as an absolute when it actually isn't, which is funny for statistics. There is an exception. Correlation does not imply causation except when it does. For example, there is a very strong correlation between complete decapitation of living people and their subsequent and immediate death. In fact, it is absolute. Nobody has survived such and lived to tell about it. So not only is there a strong correlation between complete decapitation of a living person and subsequent death, it is a causation. Complete decapitation does cause death, correlated 100%.
If that doesn't work for you, this primer should help. It goes into why correlation may not imply causation.
And the articles you posted basically provided nothing useful, certainly not contradictory. The point being, the biggest risk in lead poisoning is not consumption of lead bullet fragments but inhalation of lead vapor. The greater risk are fumes created when the primer is detonated and that you're exposed to when melting lead to cast bullets. In fact, you would have to consume A LOT of lead for it to ever be an issue.
As I said, the studies you linked to, which provide no useful data, assume that the lead present in any of the subjects tested came from consumption and arbitrarily precluded any other source.
Where to start. I appreciate that you don't like the information from the study and are demanding of more, yet repeatedly make a "crap ton" (I really like this phrase and can see why you chose to use it) of unsupported claims such as needing to consume a crap ton of lead before it shows up in the blood and that a greater risk for lead in the system occurs elsewhere.
However, the CDC article went through reviews with all the participants to identify sources of lead to which they may have been exposed. They did their homework to find a cause. You may not like the result, but then again, by your argument, you are just
assuming that the greater risk for lead in the blood (as tested) comes from fumes when the primer is detonated, or by being exposed to fumes when smelting. Heck, you are
assuming that lead got into the blood from those processes.