If I'm not mistaken that Brand is upside down. Maybe someone trying to make a buck and not knowing exactly what they were doing. Any Silver Smith supply house will make you a custom stamp.
This is not a ranch brand on these grips. This is a running letter J and M put together. The reason I know this to be 100% true is because John E. Maxson is my uncle. He was a former President of American Gunmakers Guild as well as a Master gunsmith and stock maker. I have several of his guns that carry his mark and everyone is precious. Sadly, John passed away last week at the age of 74 in Washington Court House, Ohio. If you have a stock or gun from John, please email me as we are trying to catalog his work.