You don't understand, when conservatives talk about personal responsibility, they are talking about other people.
No, when personal responsibility is talked about, it is about EVERYBODY taking responsibility. Just because you see the "conservative" politicians trying to weasel their way out of a situation, does not apply to what everybody else is talking about.
If the gun blows up because of a manufacturing defect, then there is a case to be had to sue the manufacturer if they did not take care of the problem. However, somebody taking a gun and shooting 20 children is not the responsibility of the manufacturer.