[2020] Getting spec (Crossbow) ammo fast

Could anyone help me scoring more crossbow specialisation ammo?

I really need this so I get a trophy for hitting 10 enemies with crossbow bolts in legs.

Changing specialisation and getting it back to Survivalist dont help- still 0 ammo.

I know statuses help. Killikng enemies inflicted with some status. But the drop rate is so bad that maybe creating abother agant and getting him from start to lvl30 choosing surv spec will be faster lol.

Can anyone please help me how to get this ammo fast and easy?