Since the in-game bug report functionality does not appear to work at the moment, I am instead posting the bug report here. Please let me know in case there's any alternative location I can use to report issues like this and I'll be happy to report this there again.

When performing a speed reload while having the M26 Mass underbarrel shotgun equipped, the animation that is played reloads the primary weapon instead of the underbarrel shotgun. However, when checking the ammunition pool in the bottom right corner of the screen, it is shown that the magazine of the underbarrel shotgun was indeed discarded and a new one was inserted.

Since the visuals of the game both help players keep track of what is happening (in this case, a player could assume they now have a magazine less for their primary), it would likely be worth resolving this behavior.

Steps to reproduce:

  1. Equip any primary weapon which can fit the M26 Mass underbarrel shotgun upgrade (in my case, I used the M16A4).
  2. Equip the M26 Mass underbarrel shotgun upgrade.
  3. (if necessary) Resupply.
  4. Perform a speed reload.
  5. Notice that instead of the M26's magazine being ejected, the animation shows the primary weapon's magazine being ejected and reloaded.