It's not that simple. The inquiry doesn't end with foreseeability, a foreseeable risk which is nevertheless reasonable, and which a manufacturer takes steps to mitigate once the risk becomes known to them is one for which the manufacturer does not incur liability.
Liability only attaches when a manufacturer (or other actor in the chain of commerce) knows of a foreseeable risk that arises from the sale and use of their product, and that risk is either unreasonable and the product isn't pulled, or the risk is reasonable but the actor doesn't take any steps to warn of and mitigate the harm caused by the risk.
It's worth noting, too, that the only reason Congress passed a ban on suing gun manufacturers under most products liability theories is because people had started suing gun manufacturers - and winning. The arguments in favor of liability were being heard and winning in court, so rather than clean up their act, the gun companies ran to Congress and got them to ban any further lawsuits.
So that just lays another level of absurdity on any attempts to claim that somehow gun manufacturers are the good guys doing nothing wrong. When called upon to prove it in court, they ran to the Congress they own and banned lawsuits instead. Because that's what innocent people do