[quote=gowia]
Ahh shit wrong term....Regiment is what I meant. Got the two mixed up. Apologies.
[/quote]

Still only a few thousand men there. I am thinking people will have like 3-5 planets. 1 main one like a hive world or civilized world plus like 2-3 feral or agri worlds. naturally you can have less if you want but people will potentially have billions of soldiers. The main limiter here is fleet resources to move those men.

Ships will naturally be rather rare so people who want to be warmongers can be but every time you ship out you risk your only offensive capability and with like 1-3 battleship level vessels for human based factions that will greatly limit your ability to move those billions. This means astartes based factions will have significantly higher offensive capability but more normal human based ones will have much more longevity as well as much higher defensive capability.