Everytown released a candidate look-up tool that allows you to search by zip code to see if your candidates have been named "Gun Sense Candidates." It's not an endorsement in a specific race, just a distinction that the candidate's position on gun laws are in line with what Everytown views as sensible gun policy. After years and years of NRA ratings (recently removed from the NRA's website), this is the first searchable tool I'm aware of that provides a counterweight.
Find Gun Sense Candidates in Your Area