It is not a loot radius problem but a placement problem. Some items are just under the Z axis and though you can see it, you can not touch it. Some items are lucky enough to be that but with a destructible deco which you can break and loot it. Or it's under a car you can move. Using a shotgun often throws a target into an item or just under the map. Worst is under a bush ><
Bushes are EVIL. You can see through them, you can shoot through them, you can move through them. But can't loot through them and they act as if behind cover and allow leaning.
Normal loot radius is just further then arm length away.