It would be a very different story if the politicians voting against gun reform were personally affected by these incidences. It's easy to not care when it's someone else's pain involved. Ditto for gun fetishists. Pretty sure they would turn into activists that would start doing whatever they could to stop gun violence, as opposed to the blatant 'thoughts and prayers' message.
I can only guess that these changes would happen. But yes, they do mostly come across as heartless and morally bankrupt on this issue.