Does a will supersede quit claim

My deceased Grandmother owned a farm/ranch in Montana. She had 7 children. In 1976 she made a will that was signed and notarized. It stated that upon her death she willed her oldest son a "live estate" of the property throughout his natural death. If his death preceded hers or upon his death the second named son was given " live estate" rights to property, and then upon his death the property was to be devided equally between remaining sisters and their heirs. Furthermore, she willed the mineral rights to the 5 sisters. My grandmother died in 1979. Two weeks after her death the oldest son filed a "quit claim" to the property that gave him sole ownership to property. He never mentioned this filing to anyone. This quit claim was made out in 1940 but had never been recorded, none of the other brothers or sisters knew of it's existence. (The oldest brother was one of the witnesses to the will when it was made out but never mentioned the quit claim) The brothers and sisters thought the will was in effect giving "live estate" rights to the property to the oldest son until his death. When the oldest son died his wife produced evidence of the quit claim that gave her ownership of his estate which included my grandmother's ranch. The wife has died and now her children ( the first brother's stepchildren, no relationship to my grandmother) None of my grandmother's children have disputed this claim, with only the second son still alive. My question is: Should this quit claim have taken precedence over the will having been made out in 1940 with the will completed by my grandmother, signed and notarized, in 1976?