If the ban sunsets, does Massachusetts have its own AWB like New York?

Yes we do. It passed along with the changes in the
LTC and FID card revamp. (in 98?)

drat.  Well, thanks for letting me know.

If the AWB sunsets, would it be illegal to buy new production hi-cap mags at a gunshow in New Hampshire and bring them back to Mass?

I really don't know. I will see if the law says anything about the mag ban.

No, you can buy whatever pre-ban mags you'd like and bring them to MA. You can also buy them in MA. You need an LTC-A for handgun/rifle/shotgun large cap mags or LTC-B for rifle/shotgun (but NOT handgun) large capacity mags.

Thus, if the AWB sunsets, all mags are treated as pre-ban in MA.

NOTE: Only exception is for Boston residents, they must have a special Boston-issued permit for anything high cap and I don't know their rules. This does NOT affect visitors who live in "freer" towns/cities in PRM.

Text of the state law that defines an assault weapon: www.state.ma.us/legis/laws/mgl/140-121.htm. Note references to 18 USC 921(a)(30) and specific models banned by name. If the federal ban lifts, count on the MGC to make whatever modifications it feels necessary to maintain the status quo or tighten restrictions.

Text of the Boston AQ law which was passed in 1989 (before the federal AWB): www.goal.org/MGL/boston.aw.html

JScott