I saw in the event forums that you must either use brown or green bb's on a certain field. And you will get a fine if you use any other color. Is that only for that field or is most fields like that? Because right now I am stocked up on black bio bb's. Just putting my feelers out there trying to understand a few things since I have not played in Japan yet.
Oh and the radio thing makes me sad. I had all my uniden radios shipped here for nothing. lol! Oh well time to adapt and overcome.
I haven't actually played many of the Japanese fields, but from what I've read both in the forums, online and Japanese magazines is that on the popular fields, normally any color is ok as long as they are full bio (no semi bio, full plastic or metal). That said, I did find another semi private field in Kanagawa that has the green brown rule as well.
I use a mix of white and black bio, never had any issue so far. I know Village 1 at my first game was strict on that, but that's the only place I've seen so far doing so in a year of airsofting.
I don't think it's a field thing is it? Isn't it more a public game thing? For private games at most fields would just say Bio or non-bio but they don't choose colour (up to the organisers actually and TKO we're not too fussed). But public games I see that they do get choosy.
I think it has to do with land usage and ownership. The owners of some land might be asking that the field use certain colours to hide the effects of the bbs. They will degrade, but I have read it takes a few years. In the woods, green and brown would blend in better to the natural falling foliage, etc.
Many fields don't own the land they use, and rent it off of farmers or land owners that might have plans for it in the future.