Shackelford was 11 of 19 from the arc for 35 points, 23 in the second half. His 11 treys were a record for Save Mart Center.
Fresno State improved to 6-1, its best start since 2006 when it opened 7-0.
The game was tied 52-all with 13:57 remaining. Torren Jones scored six straight to start a 20-8 run for a 72-60 lead. Shackelford's 3-pointer cut it to nine with 2:19 left but Jones had a pair of dunks in the final 1:24.
Jones scored 19 points, 16 in the second half. The Bulldogs were 22 of 29 from the free-throw line to 4 of 4 for the Mustangs, who sank 14 3-pointers to Fresno State's four.
The game was an exhibition for the NAIA Mustangs.