They are hard to find as a lot of folks like to replace the original on some guns with them,, and since they haven't been made since 1973,,,,,,,,,! Place a WTB ad in the classifieds,, but be willing to pay the price.
These were made by Alan Harton. I gave him new model SBH hammers and he cut my old ROA hammers and welded them togeather.
Total cost around $70 each
Jim