We can start by passing an assault weapons ban and background checks...
Pass an assault weapons ban.
Occurrences
Evidence
AP reported that, in Moulton's Senate campaign announcement, he said he would focus on issues including "banning assault weapons."
Congress.gov lists H.R.1808 as the Assault Weapons Ban of 2022. Its latest action was Senate referral on 08/01/2022, and the bill status was Passed House, not became law.
Congress.gov lists Rep. Moulton, Seth [D-MA-6] as an original cosponsor of H.R.1808 on 03/11/2021.
The House Clerk records Roll Call 410 on H.R.1808, Assault Weapons Ban, as Passed 217-213; Moulton is listed as voting Yea.
Congress.gov lists H.R.698 as the Assault Weapons Ban of 2023; the bill status is Introduced, with latest action on 06/05/2023.
Congress.gov lists Rep. Moulton, Seth [D-MA-6] as an original cosponsor of H.R.698 on 02/01/2023.
Congress.gov shows H.R.3355 became Public Law 103-322 and its table of contents included Title XI: Firearms, Subtitle A: Assault Weapons.
Assessments
A federal assault weapons ban was not enacted during Moulton's relevant federal service or campaign context. He materially supported the policy by original cosponsorship of H.R.1808 and H.R.698 and by voting yea when H.R.1808 passed the House in July 2022, but neither bill became law. The 1994 federal ban predated Moulton's congressional service and expired in 2004, so it cannot satisfy this promise.