Wal Mart in Oceanside has one of the largest ammo cages and get one of the largest shipments in SD. They load the case between 7-8am. The sycamore Wal Mart will sometimes release ammo the night before if you ask a manager. They have ammo because they are overlooked a lot.
Turners in San Marcos gets shipments Wednesdays. Lines start around 8-9. They open at 10am. People are camping for 22lr. Large caliber ammo is plentiful.
Big 5 In Oceanside gets shipment on Mondays. Get 22LR every week. They are heavy on large caliber ammo.
Quantico on coast highway in Oceanisde is where I have been getting my 22lr. They have been getting cases of thunderbolt for just under $300 after taxes, and are selling them all the way down to 500round boxes for the same price, about $30 after taxes.