Ruger didn't make the laws in states like Massachusetts and New Jersey, but in an effort to bring AR-15 platforms into areas that otherwise ban them by severely regulating their cosmetic features, they have a new AR-556 on the market.
With an estimated 8 million AR-15 platform rifles produced since the 1960s by a myriad of manufacturers, the gun has become known as "America's Rifle." However, a number of states and municipalities have outright bans on these guns by name and back door prohibitions on them by prohibiting the sale of rifles that have AR-ish parts such as the deadly (sarcasm) threaded barrel/flash suppressor, the assaulty (sarcasm) adjustable stock, and the dangerous (sarcasm) 30-round detachable magazine.
As such, Ruger's AR-556, which has all of these features standard, (see the above picture) is off limits to civilian sales in certain states.
Ruger's new "state compliant" AR-556 is based on the standard model but has been neutered slightly with a non-threaded barrel, given a fixed stock (that still looks like an M4 stock) with a 13.5" length of pull, no bayonet lug (because they are used in crime so often?) and comes with a detachable metal magazine that will accept no more than 10-rounds.
As noted by Ruger, this new model is legal for sale in Colorado, Hawaii, Maryland, Massachusetts, New Jersey, and Puerto Rico-- all areas where the AR-556 is otherwise restricted to LE only sales by law.
MSRP is $749, the same as the standard model.
To see the differences between the two, watch the magical transformation between deadly "assault weapon" and compliant rifle. Because gun control makes sense, right?