Frank, I have a 1900 regular frame version that has the standing bird on the left and the flying bird on the right just like yours. I've owned two of these guns the other had a featherweight frame and was made in 1911. It had a fighting or flaring pigeon on both lock plates. I have seen several of these guns and pictures of many more and I have yet to see a "Blue Rock" version. I'm beginning to believe it is the rarest version.