| Mark | Athlete | School | Year | Meet |
|---|
| 49.83 | Zannon Stands | Hardin (A) | 12 | Miles City Invitational |
| 50.70 | Beau Maus | Corvallis (A) | 12 | State A Track Meet |
| 50.78 | Ryan Hayes | Bigfork (A) | 12 | Western Montana Top 10 |
| 50.92 | Logan Harwood | Whitefish (A) | 11 | Class A Invitational |
| 51.07 | Anthony Correa | Columbia Falls (A) | 12 | Northwestern A Divisional |
| 51.26 | Jon Nissen | Laurel (A) | 11 | Eastern A Divisional |
| 51.57 | Colby Henderson | Corvallis (A) | 12 | Polson ABC Meet |
| 51.67 | Brock Butcher | Fergus/Lewistown (A) | 9 | Midland Roundtable Top 10 Meet |
| 51.97 | Luke Cardon | Whitefish (A) | 9 | Northwestern A Divisional |
| 51.98 | Derrick Williams | Columbia Falls (A) | 12 | Northwestern A Divisional |