The Blackhawk, and Super Blackhawk cylinder frames are the same. Slight differences in overall length come perhaps from the different grip frames offered. Cylinder lengths are different for each caliber however with the smaller calibers being shorter. That is done so that if someone has two guns apart for cleaning at the same time, the cylinder with the larger caliber chambers can't be put into a gun with smaller barrel dimensions by mistake. The new Vaquero's, Anniversary models, and the Flat Top .44 Specials are smaller, and I can't tell you for sure if the Flat top frame is the same size as the New Vaquero, or not since I have retired. The Blackhawks have aluminum grip frames, and ejector rod housings which makes them lighter, if less desireable in the eyes of some. A 41 mag, or .45 Colt in the Blackhawk weighs about the same as a K frame Smith, or lighter than your GP-100.