Bo4 (ps4) KAP 45 mk2?

Have just unlocked or received this special version

but we do not know where to activate them.

Have looked everywhere. Could someone help us?

That's a camouflage

Have looked. But nowhere found. Not even with the black market camouflage.

Maybe under special weapons in the primary weapon slot

Where do you find them? So in the primary slot there's no category of special weapons