Early Model Ruger SR-22 AR-15 Style Rifle -

I recently aquired an "Early Model," SR-22 with Nordic Industries accessories. I understand this model was available from 2009 -?? A less expensive version, came out to replace it, called the SR-22 ATI.

My question for you very knowledgeable folks, is when was the change made between the two models? Basically, when did they end the early version w/Nordic Industries accessories?

I have pictures posted on my thread "SR-22 Sight In," in the General Discussion forum here, of my early model.

Thank you in advance for your help/input.