So... A guy just out of military and used to firing 7.62 weapons, but unfamiliar with exterior ballistics and calculated angles of fire? Err... Hope he wasn't on 'our side'!
Concerning those "angles of fire in respect as departing from horizion...
https://www.rifleshootermag.com/editorial/hitting-a-high-or-low-angle-shot/83768Best!
John