The hammer being plain steel is standard. The finish on the cylinder being bright when the frame is blue is definitely NOT standard. It suggests that the cylinder has been refinished or replaced. I can't say which because unfortunately, your picture makes it look like the cylinder is a high-polish blue.
This was an economy model for H&R, so I doubt there were any custom orders for blue guns with bright cylinders. And in 1977, they were still doing OK, so they weren't slapping guns together from odds and ends.