Escape from Tarkov: Arena patch 0.6.1.5 limits Wildcard ammo
Battlestate says Wildcard weapons now follow the ammo rules of their own class, to fix low time-to-kill and weak armour.

Battlestate Games released patch 0.6.1.5 for Escape from Tarkov: Arena on 23 October. It says ammunition for Wildcard-class weapons now matches the restrictions of the classes those weapons belong to.
Battlestate says the change is meant to fix a time-to-kill that had dropped too low and armour that had become too weak. Rounds now restricted include 7.62x51 BPZ FMJ and M61, 5.56 M855A1 and M995, 9x39 SP-6 and PAB-9, and 12/70 AP-20.
The studio says it will run a survey after the Wildcard event to collect player feedback.
Sources: Escape from Tarkov