The .38-40 shares the same bore diameter, and Beartooth Bullets (for one example) will sell a FN hardcast in 401 or .402 diameter, that will work well in either a .38-40 or a 10mm.
I was also surprised that a 5" S&W 610 will give higher velocity than 3 different 10mm 1911's, and I expect one of the Ruger Blackhawks would do even better.
