I've googled and searched high and low but can't find any good answers.   I have a really good opportunity to pick up a few thousand of these rounds at under $0.35/rd.

I need to know the differences.  Mainly between the XM855CS and XM855AF90.  They're both 62gr, and I know at least one is steel core.  But both?

Also, for the XM193AF, it's 55gr. correct?  This is lead core also, correct?

Thanks guys.

From what I understand, the suffix on the number has to do with the contract they were manufactured for.  I think that ammo that passed quality control inspections for the .gov was just XM855.  Batches that did not make the cut and then made available to the public were given a suffix.  This would pertain to Lake City ammo as they are the main supplier for the .gov
Other manufactures may or may not keep to the standard of suffixes.  I think some suffixes have to do with the packaging.
XM185 will have a green painted tip and a steel tip in the core of the bullet.  The core of the bullet is still mostly lead with the addition of the steel tip.  Probably why the bullet is 62gr while the XM193 is 55gr.





I'd buy the stuff at less than .35 per round, sounds like a good deal to me.
Disclaimer:  Sometimes I get confused with this stuff 'cause I'm old.  This may not be 100% correct.
 

Thanks.  That's pretty much what I figured.

I would have preferred to pick up a lot of 62gr. lead core, because my range won't allow steel core.

Ah well, looks like the XM193 it is.

Where is that deal on the XM855?  Less than .35 is pretty good.

I have read that the M855 was designed for the belt fed M249 SAW.  It has been widely used as the reason "poor performance" critical of the M4.  It has to do with the wounding mechanism of the steel core round and just punching a .22 caliber hole in the enemy with no yaw/tumbling/fragmentation. It will punch a nice hole in steel though.  I'm just a knucklehead with a rifle, but all the high speed/low drag guys prefer the M193 over the M855 for social purposes.

As far as I know, it's not rejected ammo. Simply put, it meets spec or it doesn't. They're not going to make themselves liable to a KB by intentionally selling out of spec ammo to the public.

Also, the numbers/letters at the end are simply how they are packaged for retail sale. Any M855 should be the same 62gr steel core penetrator rounds. Any M193 should be the same 55gr ball ammo.

Ammo that didn't make the .gov cut isn't necessarily defective.  A batch could be rejected because of the shade of green on the tip, or the green on the tip may be flaking off, or too little primer sealer was applied, or the primer crimp may not be exactly right, or a ballistic test didn't achieve the desired result.  There are numerous reasons that ammo might not meet mil spec and the .gov would reject that batch of ammo.  And....   a failed sample would cause the entire batch to be rejected.





And, as you mentioned, the letters/numbers at the end indicate packaging for retail sale which will tell you that they are not mil spec, otherwise they would not be packaged for retail sale.





Certainly, the manufacturer would not release known faulty ammo for sale.  





just my .02




 
 

Agreed.  I did see about 2 years ago some Federal XM193 white box which read on the label in bold letters "Not for duty use.  Practice only."  Aside from any labeling like that, not meeting milspec could be for reasons that anyone outside govt. contract would not be concerned with.

It's more of a friends/family deal through a distributor.  If I could give out the deal I would, but alas, I cannot.

And yeah to everyone else, this is more just plinking ammo.  I'd rather have the 62 stuff because of my 1:7 barrel, but I doubt for practice the 55gr would make much of a difference.

For more serious situations I have a sizeable pile of handloaded softpoints.  Not cost effective for practice though haha.

1:10 is what the Swiss use to stabilize their 63 grn service ammo.  The M16A2, etc, have 1:7" to stabilize M856 - the tracer companion to M855.  M193 will stabilize in twists as slow as 1:14" if the bbl's long enough.

I almost exclusively shoot 55gr out of my 1 in 7 twist barrels. It stabilizes just fine

This should help clear up the issues with what XM ammo really is. Short version: there is nothing wrong with it.

http://www.thegunzone.com/556xm.html

Err, I thought that the tighter the twist the heavier you want the round?  I'm all confused now.

Not generally.  The heavier the round, the tighter you want the twist.  Lighter bullets will stabilize in slower twists, heavier bullets require faster twists in a given caliber.  @ extreme velocities, around 4000 fps, the rotational velocity produced by a fast twist bbl can cause thin walled varmint bullets to disintegrate, hence you tend not to see 24" bbls in 1:7" twist.

Keep in mind, twist works w/ the muzzle velocity to produce the rotational velocity the bullet is spinning @, expressed in rpm.  There's a minimum rpm for a given weight bullet of a certain length to stabilize.  As long as you're above that, you're good.

Oh man that's why I love this site.  I understand this so much better than anything I've googled yet.  Thanks!