The most significant feature is a new short stroke gas piston designed by Ruger. It shares the same benefits as other gas pistons system: a cleaner, cooler bolt carrier as the excess gas it vented out the gas block, far from the upper receiver. The AR-15 was not designed for a piston and retrofit piston systems can cause problems, for example the pressure from the piston operating rob can cause the bolt carrier to bind. It was been suggested that the Ruger bolt carrier is designed to mitigate this particular problem.
Another feature is a four position gas regulator. The first position prevents any gas entering the piston system. This turns the rifle into a single shot which requires the bolt to be manually cycled between shots. The next position allows the normal quantity of gas into the piston system to cycle the bolt. The next two position each let in more gas than the previous system which can help when the rifle is dirty or the ammunition is low powered. It is a compelling feature for reloaders because it gives them a greater range of adjustment for thier powder loads. The MSRP is $1,995. It is expensive and you could build one your self from parts for less, but if the gas system works flawlessly then I think it will be a good seller.
