Just curious as to how the gun runners restock the little hut with weapons and ammunition that the venderton is in?

There isn't a door of any sort on the outside but I did notice a wooden panel on the floor.Could they have a secret hatch though the floor?

The window probably slides open. We don't see it happen in-game, because all transactions occur on a paused menu, but Vendertron has to be able to hand us our purchased guns somehow.

Good point actually, never thought of that.But the window would surely be locked and if so how would a securitron open it?

I'm guessing the Gun Runners would have a key for resupplying it and collecting caps. As for the robot, he's got hands. Lots of windows and doors can be locked on one side but not the other.

Their not the most dexterous or nimble of hands though, I couldn't imagine him being able to open a somewhat complex lock system.

It also brings up the point if he is opening the locked window (somehow) handing you guns/ammo and then receiving caps/money then he surely must be open to attack from people?

There's no way of knowing if this is even how he does it, but it doesn't have to be complex or even locked from the inside at all. For all we know, it could be as simple as pressing a button and the window opening, or it could even be remote controlled.

And maybe he is briefly open to attack from people. But considering this is the Gun Runners, I can't imagine anyone thinks that could be a good idea.

I think it's obvious that the little shack around the robot is there solely to prevent the player from killing "Bob". It wouldn't be that hard for someone to bring the whole thing down on the robot's head or just shoot through it. I'm sure there are either other humans or robots working there in the lore. The game isn't to scale, after all.

True. I'd imagine that the whole compound is larger and better guarded than we see in-game.