Actually no they couldn't just keep the mag and sell you the gun. the gun is serialized asnd sold "with a large capacity" mag. In the eyes of the MA jackwads that make laws, it is and always will be a hi-cap firearm whether it has the magazine or not. (And this was explained to me by the owner of Four Seasons). Once a hi-cap firearm, always. So rifles shipped to MA FFLs with 10 round mags are GTG, but if that rifle was serialized as for sale in NH (ie with a 30 round mag), it's a No Go through an FFL in MA to a MA resident, ever. Stop blaming NH and NH dealers for dumbass MA laws. By federal law, any FFL making a sale has to ensure the sale is legal in the state of residence of the buyer, regardless of where the FFL is located.