Since I have the rather unusual opportunity to examine both the early Swedish m/45 and the improved m/45B at the same time, I figured this would be a good opportunity for a video. There were three substantial changes made to the m/45 when it was improved:

- Barrel proud holes made taller to make the shroud sturdier
- Magazine well guide was riveted permanently in place, as the quad-stack magazines were taken out of service.
- Receiver endcap and buffer were strengthened to better handle the new hotter m/39B AP ammunition

In addition, the m/45B guns were given a coat of heavy green paint over their parkerizing for better durability. Most of the early m/45 gun in service were updated to m/45B standard.