I found this on Massgunlaw, great site btw. I have highlighted in red where it says unloaded. I hope this helps!
Are there any places in the Commonwealth of Massachusetts that I cannot lawfully carry a firearm?
Yes. Some of the more common places include state and federal courthouses, post offices, schools and school grounds, prisons and jails, and virtually all other federal buildings and some state buildings where metal detectors are in use. In many of these places, other than schools and school grounds, if you declare your firearm at the door, you can usually check your firearm, and pick it up on the way out. Do not bring a gun onto school grounds. School grounds include parking lots, driveways, and the grounds outside the building.
A good way to declare your firearm is this: before you enter the building, get your LTC out, and as soon as you enter the building, approach the nearest security guard, hand him your LTC, and quietly tell him you would like to check your firearm. Do not reach for, display or unholster your firearm until asked to do so.
Be sure to use safe gun handling techniques when unholstering and unloading your gun. Don't be the next person to have an accidental discharge in a very public place.
If it is not possible to check your firearm, and if you are not visiting a school, you can comply with state law by leaving your firearm in your car if you first unload it and store it unloaded and locked in: the trunk of your car, a locked case, or some other secure container.
Please note, however, if you leave a firearm in your car, and that firearm is stolen, you could lose your LTC. Use your best judgment in deciding whether it is a good idea to leave your firearm behind when you park your car.
If you do leave an unloaded gun in your car, remember that it is not enough to snap a trigger lock on your firearm and leave the gun on the back seat. Instead, you must unload and carefully secure it locked in the trunk, in a locked case, or another secure container. You should expect that if the police become aware that you have failed to follow these provisions, they will probably file criminal charges against you.