Welcome to the Forum from New York. Based on the checkering and the forend cap, it looks like an older 700 ADL. 24" with that taper could have just been a regular 700 ADL. Look up the serial number on the Remington site to see the age. Way back there weren't that many sub-categories / models of the 700 ADL and BDL except for the heavy contour barrel varminters.
Could it have been rebarreled at some point? I agree in .257 Roberts, a caliber that I love, it could have had a short action, but knowing Remington, they may have just had a lot of long actions and made it that way. Post WWII with so many Mausers etc. around I am not sure people cared that much what action length they had. Does give you a lot more options if and when you want to rebarrel it.