I use the Federal Champion 9mm from Walmart fairly regularly; in fact, I just shot a couple of boxes of it through a Glock 34 earlier today, with no problems at all. It seems to be slightly more accurate than the average target/range blasting ammo (in my experience and in my weapons). It does have a few quirks that folks should be aware of, however.
It is slightly slower in velocity than similar loads from other manufacturers. I chronographed several target/range ammo types through a Glock 17 and Glock 17C, and the Federal Champion load was the slowest of the four 115 grain full metal jacket loads tested (others were Winchester/USA 100 round white box "Value Pack"; the original CCI Blazer with the aluminum case; and CCI Blazer Brass). The Federal clocked-in at an average of 1140 Feet Per Second (FPS) in the G17, while the Win/USA Value Pack ammo was moving at an average of 1205 FPS (10-shot averages for both). In the G17C (ported barrel), the averages were 1106 FPS and 1146 FPS, respectively. That is a fairly significant difference; another way to look at it would be to say the Winchester load out of the ported G17C is faster than the Federal ammo out of the non-ported G17.
The slower velocity may contribute to the load's above-average accuracy, but it also can cause problems if combined with other factors. The reason I did the velocity comparison was one of the folks on another gun-related discussion board had reported functioning problems with his ported Glock and the Champion ammo, saying it felt weaker than other stuff he had used (which was eventually supported by the chronograph results). However, my G17C had no functioning problems with the load at all. His gun was brand new, not broken-in, and may not have been lubricated before firing (as recommended by the Glock manual). Mine gun was well-broken-in, clean (the Federal load was the first load tested), and lubricated according to the manual. I did get indications that it was ejecting less energetically than the other loads, but they all ejected cleanly in my gun.
After the testing, another person pointed out something interesting; the Champion 9mm ammo has a warning on the back of the box that states: "DO NOT USE IN FIREARMS WITH PORTED BARRELS OR PORTED RECOIL COMPENSATORS." It does not say why, and the Federal Champion ammo boxes in .40 and .45 (see edit below) do not display the same warnings. Is it because the 9mm is so weak that it may not function well in comped/ported weapons, or is it something else?
EDIT, 2-12-11: I have now seen .45 Champion ammunition boxes with the "DO NOT USE IN FIREARMS WITH PORTED BARRELS OR PORTED RECOIL COMPENSATORS" warning, so it is not just limited to the 9mm loads as I originally said above.
On the subject of "something else", when accuracy testing several different weapons with the Champion 9mm ammo, I noticed the bullets from one box appeared visually different from the bullets in another box. One was a normal-looking copper-jacketed bullet; the other looked more like a plated lead bullet. It was strange enough that I took a picture of one of each of the rounds standing side-by-side (one also looks a little taller than the other, too):
I assume they are just buying the cheapest bullets in bulk, which vary from purchase to purchase (might even be different makers). I've seen similar changes before in less expensive 9mm ammo; years ago, the WWB Value Packs had a bullet with a strange greenish tint, and then at some point they went to a more normal-appearing copper-jacketed bullet. Even bullets in expensive defense ammo will change slightly over time (I know of several different types or "generations" of Gold Dot JHP bullets, for example).
Anyway, it could be that folks have heard about or noticed one or more of the above items and made an informed decision not to use the Champion ammo, which would explain why it seems more plentiful on the shelves. As for myself, I've made a note to no longer use it in my ported weapons, and if I need a larger quantity for accuracy testing or a competition, I always match-up the lot numbers on the box end flaps to make sure I'm getting ammo from the same production batch. I will continue to enjoy the cost savings ($10.47 per 50 here), lower recoil impulse (faster follow-up shots in the competitions!), and better accuracy (in my weapons, at least) that the Federal Champion 9mm ammo provides.
(I am not connected to any ammunition manufacturer or seller in any way, nor did I profit from, or receive any free products for, this report).
"Placement is power" -- seen in an article by Stephen A. Camp
(RIP, Mr. Camp; you will be remembered, and missed)