Remington made a change to the frame on the latest non-"ERPC" marked" R1 models. There was a lot of customer complaints about the slide stop overhang on the older Remington R1 models. Most people know that on the older ERPC marked R1 models, the bottom of the slide stop would overhang the flat of the frame above the trigger area. NOT ANYMORE. The latest non-ERPC marked R1 models no longer have this ugly overhang problem. You can also look at pictures of the right side of the frame of both ERPC marked and non-ERPC marked R1 models and it will be very clear to see the difference in the amount of space from the center of the slide stop shaft to the flat of the frame above the trigger area on these two frames. Great improvement Remington ! This slide stop overhang on the older ERPC marked models really looked like hell. It's nice to know that Remington Arms is a company that listens to it's customers and is committed to customer satisfaction by constantly striving to improve and update their products. Again, great job Remington !