| Mark | Athlete | School | Year | Meet |
|---|
| 49.21 | Dylan Cervelli | Beaverhead Co./Dillon (A) | 12 | State A |
| 49.74 | Jack Waddell | Park/Livingston (A) | 10 | State A |
| 49.97 | Jay Beagle | Libby (A) | 10 | State A |
| 50.00 | Lee Walburn | Whitefish (A) | 12 | State A |
| 50.56 | Cutter Thatcher | Butte Central (A) | 11 | State A |
| 50.71 | Drew Morgan | Columbia Falls (A) | 12 | State A |
| 50.93 | Taggert Devaney | Laurel (A) | 11 | State A |
| 51.19 | Kaiden Romney | Frenchtown (A) | 11 | KLH Memorial Track Meet |
| 51.45 | Jess Bellows | Custer Co./Miles City (A) | 11 | Midland Roundtable Top 10 |
| 51.54 | Boston Goode | Polson (A) | | State A |
| 51.72 | Hunter Bear Cloud | Hardin (A) | 10 | John Polich Invitational |
| 51.90 | Paul Little Light | Hardin (A) | | State A |
| 51.97 | Justus Peterson | Beaverhead Co./Dillon (A) | 11 | Western A Divisionals |