I think it is no longer legal to exchange ammunition, powder, and primers. I'm no authority on it but I do recall having heard that a time or two.
Please understand, I'm not intending to offend you in any manner what so ever, after all the following is only my personal opinion, and is worth no more than that. So far as using the powder for another application, it could be a bad experience. The powders used for almost all factory ammunition is not canister powder, so knowing it's relative burn rate, thus appropiate charge weight, would be a throw of the dice. Whether or not it will perform well would be the least of my concerns, but more so, how will it react, especially since you mentioned your Grand Children being the ones shooting these loads that were developed without an established base line. It would be no different than ripping the lable off of 25 or so different rifle powders so they are unidentifiable, and then aimlessly picking one, and then picking a charge weight out of thin air. Another concern I would have is not knowing if the manufacturer used the same powder for all of those boxes of ammunition. I would imagine manufacturer's will change powders in mid production becuae they may have run out of the first one, and decided to use another one to complete a run for that lable that performs with simular ballistics even though it may have a completely different charge weight and burn rate.
I would sell the rounds and use the money to get what you need for your desired application. For that matter, I would be interested in buying those rounds off you if your interested in unloading them. I don't like factory ammunition, but I'll shoot it for the brass. PM me if you want to sell them so we can discuss shipping costs, and what you want to get out of them.
