I suspect that the garrison in US Scourge is bugged due to the garrison not being on the map at all upon it spawning, and the structure not rendering when I had arrived to check it out after a few minutes of it spawning. It was stone grade from the two stars on the notification. Everything except for the turrets in the garrison had rendered in. Oddly enough, they were not shooting back, even after I authed and deauthed myself on all three turrets, and even with my teammate nearby. I waited for a brief moment, though nothing else was rendering in at all. After a bit of ingenuity, I was able to obtain the turret's weapon, ammunition and even the item itself by authing myself on a TC placed on a foundation within close proximity, then smacking it with a salvaged hammer.
TL;DR: US Scourge Garrison doesn't pop up on map, only turrets appear, turrets don't fire at anyone, and you can yoink turrets / ammo with TC and salvaged hammer.