I was actually just talking to someone who has a SCAR17 and says it is the best 308 he's ever had or used, which is saying something for him. He had a couple of his buddies shoot it and they liked it so much they each went out and picked one up too. Of course you need like $3000 to blow. Can we even get those in MA? I would loved to be proved wrong but I doubt they are making a MA legal version with a fixed stock and no threads on the barrel.
They come with a PWS brake which you can get pinned. You'd also have to pin the stock. Do this and it's MA compliant.
However, mags are a bit of an issue. FAL mags can be modified to work but otherwise you're limited to 10 rounders.