Sorry to duplicate this, but can't reply to the other thread.
The.White.Hat, You asked this question.
This issue is very strange.
Can you please tell of your setting to 'auto-switch' ammo is set to ON?
And if it is mind turning it OFF to see if that keep happening?
I tried this and it didn't matter if the auto-switch was off or on. It still switches back to the ECO's from Hellstorms randomly when jumping portals. Annoying when you find yourself in a firefight on the other side. lol
Hope that helps.