Yep, its alla big heap. when gunmakers and ammomakers are selling their wears, they make a certain model, and each of that same model are going to be exactly the same. If you buy a Marlin 336C 30-30 from walmart or your gun dealer, the next day its still going to be a Marlin 336C 30-30, no store attached. It is true that walmart does have the price advantage which most smaller competators think of as unfair, so that is why they start slinging mud.
If you think about it, if that were true, the gun manufacturer would be at fault, for making a lower quality product, wally world just sells it.
Its all about economies of sales, higher volume, lower prices, just how it is.