Both comments are in the same direction, but you’re not technically wrong.

https://giffords.org/lawcenter/state-laws/ammunition-regulation-in-massachusetts/

Require a license for the purchase or possession of ammunition

What type?

State law requires applicants to pass a background check to verify that they are eligible to receive a FID or License to Carry, as described below. Massachusetts also generally requires all first time applicants for FID Cards and Licenses to Carry to complete a certified firearms safety course or qualifying hunter education course and submit a certificate verifying that they completed the course with their application for an FID or LTC.7

Not clear there, maybe in the law. Is that license registered federally? The claim was that Massachusetts law required them to do that.

I don’t really care either way, because long story short, it’s easier to be dismissive of this from an apriori stance than from a researched one. Federal protection applies to states, which means Massachusetts can get bent whether this is fully factual or not, and there are more important things to burn research time on.

Commies can lie faster than people can research, so spend time where things are codified, not easily dismissible, and should actually be fought. Your note is appreciated, so not to be rude, just if you want this specific claim dismissed by facts, bring your own sauce. If there is an actual law making it hard to sell ammunition, vendors in MA will need to find ways to beat it.