His obituary states that he crossed the plains to Utah the same year that James B. Cox was murdered. That happened in 1850. Unfortunately the obituary misidentified the year of his overland travel as 1846, but there is no question about the date of the murder. It was mentioned in many trail diaries as happening on June 7, 1850.
He is seen on the plains in 1857 with the Homer Duncan Company. He only traveled with this company from Ellis County, Texas, to the jumping off place on the Missouri River where Duncan's company began going west (possibly Atchison). At this point he continued up the river to Independence where he joined a small company of Utah-bound Mormons, including Apostles Snow and John Taylor.
His surname is also spelled "Gammell" in some sources.