I have been lurking and have read the ammo FAQ.  It was very informative and appreciated.  After reading the comparative stats on the faq, I fail to see any advantage for using the 855 over the 193.  From the above set up and for urban type engagements, it seems like the 193 outperforms the 855 in almost every way, (fragmention, tumble, penetration, stability).  
Am I missing something that makes the 855 preferable?
Also, are some of the recent stories of the problematic military performance (failure to tumble/fragment) of the 855 due to the above shortcomings?  Would 193 better serve the military units using M4 type weapons for urban combat?
Thanks  

Agree for general purpose use the M193 is the way to go, in particular for most hand fired M16 "carbine" type uses.  However, IMO there are a few areas were the M855 or a expanding round (e.g. Hordany TAP or one of the 75 grain hollow points) are interesting options.

Design points discussed in the early days for the SS109/M855 was beign able to go through a military helmet at a distance and better performance in the SAW type weapons at that time being considered to replace the M60.

When shooting some type of hard targets (i.e. steel) friends found some of the SS109/M855 to have better pentration, in particular the old Hertinburg (sp?) which when cross sectioned had a harder steel core than USGI/IMI/Candiana etc.

The tip was also "better" formed, if can still find the Xrays will post a link later.

You should have lots and lots of both [;)]

Joe

MS;

Don't ask us, shoot both over sandbags and let it tell you which one it likes. Shoot at least 10 shot groups, though.

Let us know.
Cheers!
Him

Yes, intended use through a 16 A2 carbine.  My understanding is such a short weapon cannot provide the velocity or stability to engage targets much past 200m and the 855 shortens this effective range further.