In my Swiss' handle I can keep an extra 7 rounds of .223Rem...and some toilet paper (to stop the rattling).
EDIT - Just tried again as was able to fit 8 rounds...not to shabby and still had some room to jam toilet paper to stop any movement/rattling.
I think I may/its a general good idea to possible store some soft point ammo in your grip...keep it the same gr. weight as your standard loads so it will match your irons/scope settings but gives you a much better (emergency) hunting round then a standard FMJ. ***this is really one wise for a non-restricted rifle***