http://lincoln.ne.gov/city/attorn/lmc/ti12/ch1208.pdf12.08.200 Weapons Prohibited in Parks and Park Facilities.
(a) It shall be unlawful for any person to possess or discharge, or cause to be discharged,
within any park or park facility, any firearm, including, but not limited to, any pistol, revolver,
shotgun, or rifle.
(b) It shall be unlawful for any person to possess or discharge, or cause to be discharged,
within any park or park facility, any air rifle, bow and arrow, crossbow, toy pistol, toy gun,
slingshot, or any other air, gas, manually operated or spring operated gun, weapon, apparatus, or
instrument designed or intended to be used for the purpose of throwing or projecting missiles of any
kind by any means whatsoever, whether the instrument is called by any name set forth above or by
any other name.
(c) Notwithstanding the foregoing, the Director of the Parks and Recreation Department
may designate areas in certain parks and park facilities to allow various organized programs to
engage in the activities described herein.
AND NO SIGNS. But if you want to be the test case have at it.
Link you might like to look at.
http://handgunlaw.us/documents/NECityLaws.pdf