I know this is somewhat of a necropost, but I feel that I have some knowledge to share with you guys, that may help you in the future, about what's a legal, and what's a non-legal, field.
First of all, any government owned lande, whether it's city, county, state, or even federal, is DEFINITELY A NO GO. You will never get permission to play here, and especially not where you will have control of what you do and when, at your free will. You're trespassing, as well as breaking way too many laws. Stay well away from any government property (Jericho Pendleton is excluded from this, as we're 100% legal).
PRIVATE PROPERTY:
You also cannot legally play airsoft on private property. 'You can play there with landowner's permission', is a myth. When push comes to shove, you cannot simply run out into your property and shoot guns, regardless of what people may tell you. Whilst airsoft guns are not firearms, within many city limits, they are under the same laws as real firearms. If somebody calls the police, or the sheriff, regardless of whether you have written permission from the landowner, you have not got legal clearance.
In addition to the above, without liability insurance, and a signed waiver from the day the person played airsoft, the landowner can get sued for uinjury at any time. Don't believe this won't happen to you, as a large medical bill for say a broken limb, would mean most people would sue you for the money.
Thirdly, it doesn't matter if you know everyone playing, or you've never met them before, you're still breaking the law.
PERMITS:
Within city limits, most cities cover airsoft in teh gun ordnances, so it's illegal to fire an airsoft rifle within city limits, they therefore, will not issue you a permit .
County property (by this I mean private land, under county juristiction) is the best solution for an airsoft field.
A Conditional Use Permit is required by county law, in order to operate a legal airsoft field. Usually a permit can cost anywhere from $50,000 to over $200,000 dollars to get established.
You will also need additional permits if you wish to build structures over 6ft high. Even with a CUP, you will still need planning permission and special permits for structures such as buildings, etc.
Without the correct permits, you cannot operate an airsoft field.
ANOTHER AIRSOFT MYTH:
I have often heard players of certain fields, say that their local police dept have an 'understanding' with them. This is NEVER TRUE. I have played at fields where sheriff's sons have played, and sheriff's have watched the game while on duty. Whilst that particular sheriff is not reporting the crime, it does not make it any less legal. A lot of sherriff's and cops do not understand the full legalitoes of airsoft, all it would take is a little research on their part, liek calling it in, and they'll be made to shut you down. Just as Sherriff's and Cops don;t have 'agreement's with bank robbers, or domestic violence, they will not have an understanding with you, either. I've skateboarde in many places where the cops won't arrest you or bother you, even though it IS illegal to skate there, but if it's called in, they have no choice but to act.
Playing airsoft anywhere other than a legal airsoft field, is ILLEGAL.