Carrying a long gun

In GTA 5 a carbine and a rocket launcher travelled in the same invisible place as your phone, and nobody on the street ever noticed. Nelson says that is over. A long gun is an object you have to have brought with you, and getting one means going to a locker at an Ammu-Nation or opening your own vehicle.

The distinction is the whole system. A rifle slung over your shoulder is something the world tolerates, and almost nobody reacts. The same rifle held in your hands empties the pavement in front of you and is enough on its own to get you stopped by police. One posture is a man carrying a thing, the other is a man about to use it.

Nelson's reasoning is about consistency rather than difficulty. A world built with this much detail cannot also let you walk down a busy street holding a carbine while nobody looks up. It is the same argument behind the wanted meter needing a witness: the world is supposed to notice things.