I dont get why they use rifle calibers for for hunting. They seem so ineffective. They have pour tons of rounds into even small monsters to bring them down. We already saw that ogres can take multiple anti tank rockets to bring down. 556 rounds would be like spitballs. Not to mention all the ammo you would have to drag around.
I would expect stuff on the larger calibers with specialized payloads. Like 12 gauge or larger shotgun shells, 50/338 cal rifles, heck even anti tank rifles were a thing in ww2 running calibers up to 20mm.
So then this begs the question, if small arms fire works on monsters, why do they need hunters to be the one pulling the trigger? Lets ignore the fact that militaries have tanks and stuff for now.