According to the ATF database, there are 5 registered FFLs in Gladstone, Missouri.
7015 NORTH OAK TRAFFICWAYGLADSTONE, MO, 641180000
6120 N BROADWAYGLADSTONE, MO, 64118
4000 SHADY LANE DRGLADSTONE, MO, 64119
3000 NE BROOKTREE LANE SUITE 106GLADSTONE, MO, 64119
205 NE 74TH TERRACEGLADSTONE, MO, 64118