Quoted:
Any MASS resident can come to ME, RI, VT, NH, or CT and buy all the ammo he can load in his car and drive it home. A buddy might even have 'overbought' from one of the national suppliers and would be willing to sell to you at that price. The same, I would think, would go for ammo you own even out of state. It's a private purchase. Does the law address private purchases out of state between "friends"?
Rome
As previously stated, there are companies that will ship ammo to MA residents (not many, but a few).
The issue with buying in bulk across the state line and driving home is the MA "sales
& use tax." The state tried to enforce this with alcohol purchased in NH several years ago. There is the possibility that the state could require you to pay the tax on any ammo bought out of state.
We are only one step ahead of Russia or China here. The state wants to control everything and redistribute any wealth left over to the folks who don't want to work so they can pump out more welfare babies who will vote for more welfare funding when they grow up.