On June 29, 1892, Musser was called to the 16th Quorum of the Seventy, and two years later in April 1895 served a mission in Alabama, having been set apart by Brigham Young, Jr., Heber J.

On Thanksgiving Day 1899, in the company of four other couples, Musser and his wife, Rose Selms Borquist, received their Second Anointing at the unusually young age of twenty-seven, under the direction of Lorenzo Snow.

He was excommunicated from the LDS Church by the high council of the Salt Lake City-based Granite Stake on March 21, 1921[6] for attempting to take Marion Bringhurst as his fourth wife.

In May 1932, Musser married again, this time Lucy O. Kmetzsch, and on the May 14, 1929, he was ordained an apostle in the Council of Friends by Lorin Calvin Woolley, the then-leader of the Mormon fundamentalist movement.

Other leaders also took issue at Musser's condemnation of the practices of underage and arranged marriages that were going on in the Short Creek, Arizona Mormon fundamentalist community.