WalMarts are all different, but there is usually one in your area with the most guns/ammo than the rest.
Each department is like its own mom and pop store.
At the last two places I have lived (both big city WM and small town WM), I went in enough to know who worked sporting goods, who ran it, when they marked stuff down, etc etc etc.
It is all about relationships. Treat the folks that work there like....... people and you will be amazed at what they will do for you. And you will make a new friend or two in the process.
I have had my local WM guys do the following for me:
Call me on my cell about ammo they were marking down for clearance and asked me if i wanted them to hold some back for me.
6 box limit on ammo? Not for me.
Called area manager at home to see if something could be marked down
more for me. (muzzleloader display model)
Invited to quail hunt (I fo'ed and it was fun!)
Treating people like you want to be treated is not only the right thing to do even if you never 'get' anything out of the deal, but also you often do reap tangible rewards.
People are people whether they work for GI Joe's Tactical Heaven or WalMart.