Your aspirin strawman is not analogous. And you are ignorant of the law in your subsequent posts. NM law is very clear on what negligence and manslaughter are. You wanting to re-assign responsibility to a gun maker or someone other than the person handling the gun does not make a legal argument.
Here are the tests for criminal negligence:
1) The defendant acted so recklessly that they created a high risk of death, and/or major bodily injury;
2) That the defendant’s actions showed a disregard for human life, or an indifference to the consequences of their actions
3) Any reasonable person in the same or similar situation would have known that the actions would have probably resulted in harm or death to other people.
If someone is handed a gun by a professional armorer and told it is a cold gun, there is no chance the case would survive 3).