I was in a gun shop in MA today and saw a box of 30 round mags so i took a look they all appear to be post ban is it even legal for them to posses and sell them?
Many FFLs also serve as suppliers for the local police departments.
I've gotten fooled a couple times myself, getting all excited after coming across some nice looking magazines in a shop, only to learn they're new post ban mags for the city cops.
Exactly - how do you think those little hole-in-the-wall shops stay in business? Their primary business is commercial sales, and they operate a public retail store as an after thoughts. Lots of FFLs like that in Mass (many don't even have a storefront).