Different br of the Puma VJTF and KF41

Why does the Namer 30 have a different battle rating (BR) compared to the Puma VJTF and the KF41? All three vehicles are equipped with a stabilized 30mm autocannon, two loaded Spike missiles, and two spares. So why is the Namer 30 rated one BR lower than the other two? I believe all of these vehicles would perform well at a BR of 10.7, just like the Namer after the BR changes.