I searched and found minimal info on this, and no real answer.
What’s the difference??
I see ammo-to-go has Federal XM193 on stripper clips, XM193 in the brown 20rnd boxes, and XM193C also in 20rnd boxes, but they are black. The “C” is about $4 per 1000 cheaper, but I don’t see it listed as to what the difference may be if any… Just the cool tactical black packaging?
Or does the “C” help me keep from getting colds and scurvy? 
Argh!
-RD62
Thanks for the link!
However it still failed to explain what if any difference their is between the XM193 and the XM193C.
Although, seeing as how the suffix “PD” apparently denotes a bulk packaging. It stands to reason that the “C” suffix may simply denote “Commercial” packaging.
Can anyone confirm if that is the case?
Thanks!
-RD62
Not really. Unless you can figger out what the “A” stands for on the stripper clip packed XM193.
I read about this a long time ago and can’t remember any of the sources, errornet of course being where I found them. There were two different schools of thought on the difference, or not, between XM193 and XM193C:
1.) XM193 “C” denotes commercial ammo to be packed in the black “tacticool” box. There is no difference other than packaging and price between the XM193 and the “C” loads
2.) XM193 “C” is cosmetically more appealing and are loaded into commercial boxes while blems are loaded in the brown box labeled XM193.
I don’t know which is correct. Maybe none are correct. My friend bought the “C” and I bought the regular. There looks to be no external difference, potentially squashing the “blem theory”. All of my ammo has been clean and I have had no failures, neither has he. Interesting that you say the Black box “C” stuff is less expensive? Around here the Black box “C” stuff is $23 MORE per 500rds!!! Maybe being “tacticool” isn’t as big of a phenomena by you as it is with all the Yahoo’s where I am. I need to move. LOL
I didn’t know the Black box was being produced concurently with the NON “C” ammo.
I just figgered they finally decided to start putting this ammo in a presentable box for retail sale. And that the “C” differentiated it from the “A” on the stripper clips. I haven’t noticed the black label stuff commanding any more money than any other color of XM193 box.
Like I said in my earlier posts, ammo-to-go has both in stock and the “C” is negligibly less expensive, $4 per 1000rnds. It 's packed in different boxes. But I can find no other differences.
For me the regular XM193 has always worked flawlessly, so there isn’t enough savings to worry about swapping.
It is probably the same, just different packaging. I’ll try and email Federal and see what they have to say…
-RD62
I sent this email to Federal:
I have seen two different Federal 55gr 5.56mm loadings, XM193 and
XM193C. There is a packaging difference. Are there any other differences
between these two offerings? Thank you!
I received this reply this afternoon:
No, it is strictly the packaging.
So from the horses mouth. I guess I should have just asked them in the first place! 
-RD62