Junior, High School, Amateur and College Golf before GW
Muir was highly recruited out of Canyon del Oro High School in 2000 and started regularly during the 1999-00 and 2000-01 seasons at the University of Louisiana-Monroe, then known as NW Louisiana. As a freshman, he averaged 77.52 over 17 rounds. He averaged 77.07 in 29 rounds as a sophomore and finished in the top 20 twice, first at the ULM Classic with a 223 total over 54 holes and again at the Nevada-Reno Classic with 217. As a junior golfer, Brandon finished fourth at the IJGT Tucson Classic in 1998 with 79-74. He also finished second with 69-69 at the Arizona U.S. Junior Amateur Qualifier to advance to the U.S. Junior. At Conway Farms in Illinois, he shot 158 (one shot behind his friend and University of Arizona standout Ricky Barnes, the Low Amateur at th3 2002 Masters) only to miss the cut by three shots. In 1999, he finished second at the JGA Ping Junior Masters with 75-72. He also shot 69-72 to finish third at the Phoenix Junior.
In his first semester at GW (fall 2003) Muir became a steady presence in the middle of the line-up. He opened his Colonial career with two 73s at the Navy Invitational, to place 18th. He shot his career low 70 at the James Madison Invitational with where he shot 78-70-71. Muir's best collegiate finish came at the Rehoboth Beach Fall Invitational where he shot 77-73 to finish ninth. Muir struggled to crack the starting five in the spring of 2004, but he was a part of the tournament winning squad at The George Washington Invitational in his only spring start.