So true, CGA, you will never get 6 gals per minute from a Hypro 252 pump after the friction of 300 feet of hose. 2.5 gals per min is more typical; the 404 pump might be a bit better.
I am glad to hear you mark your "leftovers" jugs with what is inside and the concentration.
All of us have to be careful about chemical mistakes. You don't want to cause a problem and convince your local polictican to add more regulations.
A regular labeled Roundup jug would not be correct as the concentration of the dilute solution would be much less. I guess the only proper way to do would be to cover up the original concentration, and then label the jug prominantly as the dilute solution (2 Percent in big bold letters).
You definately do not want to apply the concentrate when you intended to apply the dilute solution. And do not measure out the dilute solution when you think you are using the concentrate. Don't gamble...don't apologize.