Donald Trump’s shifts on gun background checks after mass shootings https://www.massshootingtracker.org/ http://www.trumptwitterarchive.com/ https://twitter.com/realdonaldtrump/status/306876994497413120 https://twitter.com/realdonaldtrump/status/326288159816183808 https://twitter.com/realdonaldtrump/status/335238149418659840 https://twitter.com/realdonaldtrump/status/966119932793585664 https://twitter.com/realdonaldtrump/status/966662241977360384 https://twitter.com/realdonaldtrump/status/967389553362423808 https://twitter.com/realdonaldtrump/status/969178931369783296 https://twitter.com/realdonaldtrump/status/973185831547670529…