I am not sure where Palm is, (Southtown?) but I bet the Aero store isn't too far from you. It's just north of Qualcomm, take I15 and exit at Aero, turn left, then turn left at Murphy Canyon.
With the huge Murhpy Canyon military housing right across the freeway, that Wal-Mart sees Marines, sailors, etc in there pretty frequently. Park by the garden section and it's that much quicker.
Once you get done, you can check out American Shooting Center just south of MCAS Miramar.
Hopefully it works for you at the Palm store, but you should not have to provide that much documentation just to buy ammo.
If I am wrong and Palm is in Oceanside, then the San Marcos store is not too far at all, just head east on 78 and take the Nordahl exit, (Last one before I15.) Turn left over the freeway, Wal-Mart is left of Nordahl, Turner's is right. On your way back to Ocenaside, visit Ironsights by the airport, a very friendly range.
Good luck.