I'm really struggling to find a match for this 1957-D RPM... Ive looked on Coppercoins.com, VarietyVista.com, doubleddie.com and checked a couple publications. Not sure if there is some PM damage thats throwing me off? Any help is appreciated. I have more pictures but not sure that they will help. Photography is a whole other can of worms.
Not sure if that might be an RPM or a die chip. Are you referring to an extra "piece" of vertical bar west of the primary MM? There is a chip on the 9 so that makes me think this is a later die state coin that is prone to odd chips and cracks in 1957.