How much weight can bed rails hold?

I've seen a few people like this guy who used an ammo can and mounted it to the bed rail. I see that some of them are free floating. How much weight could you put in an ammo can hanging off the bed rail?

An example of what I'd like to do.

http://www.tacomaworld.com/forum/2n...acks-tie-downs-brackets-covers-whatevers.html

 

200 lbs i doubt you could overload the ammo can enough to break the bed rail

 

Perfect thank you very much!

 

Is it just attached at the slider thing? If the weight was distributed evenly along that rail I am sure it can hold 200 lbs easy. If most of the weight is at the bottom of that can it may become a little wobbly through the ruff stuff

 

I have 25ft of 3/8 chain as well as the winch adapters for my highlift in an ammo box mounted like that and it doesnt budge. I have a 1/2 carrier bolt in each bed rail with a nut inside the box and a lock on the front.

 

Exactly the same thing I was thinking on how to mount it. I don't think I'd have more than 75lbs max at any giving time, more so 20-30lbs. Just didn't want to drill holes in my ammo can and mount it before I knew it could hold some decent weight.