You can get an unrestricted non-resident CCW permit in Massachusetts, but you have to be willing to jump through the hoops correctly. The hoops are a pain, but they can be negotiated by a careful and determined person. The hoops are designed to a) collect money, and b) weed out casual people who aren't dead-on committed to having the non-resident CCW.
As others have said, you need a good reason for them to issue you an unrestricted license. I earnestly believe that most people can come up with something, if they're creative. Don't lie, just be creative if you have to. In my case, I had a childhood friend who became a narcotics dealer during his twenties. This particular individual kept trying to contact me despite telling him I wasn't interested in resuming our friendship. So, I argued that I felt I needed to have an unrestricted CCW permit for self-protection, since I live near the Mass border. Easy-peasy... an unrestricted non-resident permit was granted.
Once you get the unrestricted permit, it's much easier to get it renewed each year. You still have to fill out the form that describes the reason for the unrestricted permit, but I just copy the same text from year to year on every application. After the first year, they didn't even ask me about my reasons for "unrestricted" in the interview. I've renewed my unrestricted non-resident permit for 5 years now, and after the first year they've never asked me again about my reasons for wanting an unrestricted CCW.
As others have said, they are a bunch of hoops you must jump through to get the non-resident CCW for Mass. You have to plan ahead and make sure you get all your ducks in a row, or you they just return the application to you on a technicality. Be prepared to deal with the following minutia, "every year", year after year:
1. $100 fee every year. This means a special trip to the post office to get a postal money order for $100.
2. Fill out the 3 page application every year. They just revised the application in 2015. Save a copy of your application, so after you get approved the first year, you can copy the exact same words for subsequent renewal applications.
3. When you renew, make sure you answer the question "Have you ever held a firearms license in any other state, territory or jurisdiction?" with "YES", and list "Massachusetts" as the location and provide your current Mass non-resident CCW ID number.
4. Scan a copy of your town's local CCW permit, and save it so you can re-print it each year on renewal. You need to include this in the application "kit" you send them.
5. Have some standard envelopes and stamps available so you can quickly & easily create a self-addressed stamped envelope. They require you to send this with your application "kit" so they can mail you your new CCW license.
6. The first year only, you need to have a copy of your certificate for a Mass-certified firearms training class. After the first year, you don't need this anymore.
7. Get some full-size priority mail cardboard envelopes to put your application "kit" in. The kit includes: $100 postal money order, 3 page application, copy of local town CCW permit, copy of Mass-certified firearms certificate, self-addressed stamped return envelope.
8. Understand and be prepared to go to Chelsea MA for an interview every year. Your schedule needs to be flexible enough to show up on the date/time they give you. You don't get to pick the date or time. Asking them to reschedule will cause months of extra delay.
Get all this stuff organized so that each year the renewal is less painful. Once you get the unrestricted non-resident CCW, don't let it lapse-- the interview is much easier when you renew an "unrestricted" than to get a new one. Which brings me to the next point: be prepared to plan MONTHS in advance, every year for the renewal.
The non-resident permit is good for only one year, but the whole process takes at least 4 months (sometimes 5), so you have to plan many months ahead to avoid a lapse. In my case, my non-resident CCW expires each year in May, so I submit all my paper work in December. After you submit your application "kit", it takes a few weeks and they will email you a date/time for the interview. The date will be many months away, so it is important than you submit the paper work at least 4 (if not 5) months in advance of when your old license will expire. Make sure you can get the time off from work (it will be during the day on a weekday).
Show up for the interview dressed as though you are taking your wife/girlfriend to a nice dinner. You don't need a suit or tie (that would probably raise red flags), but don't be in scrappy jeans and t-shirt either. Something like khakis and a simple button-down shirt is good. When you talk to the interviewer, talk as though you really earnestly believe you need an unrestricted permit. Don't sell your case short, even if you've been a little "creative" with your reasoning for an unrestricted CCW. In my case it was "Yes, this childhood friend now has a long criminal record from narcotics and weapons charges. I've told this person not to contact me but they keep contacting me against my will. I absolutely DO feel that I am much safer with a means of defending myself."
The interview is an exercise in passing the proverbial "smell test". They don't have time to verify every detail you tell them-- they're looking for red flags in your presentation that suggest that you're bull-shitting them. That doesn't mean you should take the liberty to outright lie, but you do need to BELIEVE IN YOURSELF when you speak, and you should speak with conviction. Be natural; don't be cocky; be down-to-earth; project a "reachable" demeanor; be believable. If you combine a good presentation (no red flags) with some kind of reasonable reason for an unrestricted license, you will probably get one.
After the interview, you will receive the license in the mail in a few more weeks. Last year (in 2015), they were backed up and it actually took almost 2 months to get the license after the interview. I can't say it enough-- plan ahead (months) so that your non-resident CCW license doesn't lapse.
Good luck.