As long as your friend is willing to drop a lot of cash on pre-ban guns and if he lives in a gun friendly town, then he should have no problem getting a carbine or whatever long gun he can afford.
As Freepster outlined, the first step is to meet with the chief and apply for a LTC Class A. Don't bother with the others license types. Assuming he is approved, then he needs to find a dealer he likes and then find the pre-ban carbine he wants and have it shipped to his dealer. As long as the gun is truely pre-ban then he should be able to purchase it.
Pistols are another story and he is relegated to SIG, Berettas, S&W and a handful of other manufactures that submitted guns for testing and were signed off by the AG.
Recommended Dealers in eastern MA are
Four Seasons or
We Are Guns. There aren't any real good dealers in Central MA / Worcester Area, but you can always try The Gun Room in Shrewsbury if you can't make the drive to the other two in Eastern MA.
Good luck.