Broforce Airsoft has the best brands of bb's in it's assortment, including; Xtreme Precision, G&G, Nuprol, Madbull, Geoffs & Green devil. We only sell certified biodegradable bb's, so you can play on all Dutch and Belgian pitches without any problems.
If you are going to play outside, it is important to shoot with heavier bb's. External influences can prevent light bb from flying nicely in a straight line. .25g. .28g & even .30g bb's can be used outside. It is important that you are sure that your hopup unit can hop these heavier bb's and that your Joule output is sufficient to ensure that you do not lose too much range.