Make Combat Shotgun available at Military 3 research and possibly push Tank futher into research tree, either into Military 4 research or separate research the requires either Production or Utility science and has Military 3 as prerequisite.
Why?
While it was pretty nice that shotguns received a buff, Combat Shotgun still feels largely irrelevant because it requires you to produce Utility science, which is pretty late for personal weapons, especially because Tank is available in Military 3 which requires Chemical science and it is more powerful than any personal weapon at least until nukes come into play. So perhaps it would be a good idea to make Tank available later while giving Combat Shotgun earlier to make weapon progression a bit more meaningful.