Model 13 and Fierra DB12 don't have models for struck primers, which indicates a fired round. Without that visual indication there's no way to visually determine the status of the loaded rounds through the animation alone.
Most magazines also lack followers, with just a gaping hole where the rounds are magically fed through
M7A1's magazine is particularly lacking, with no follower, no feed lips, no specific model for 2(+1) rounds remaining, no model for the hybrid-cased military ammunition, and modeled rounds being sunken into the magazine body