ok, I'm confused.  Fackler states that M-193 is effective at fragmenting to 200 meters and that M-855 tops at about 150 meters.  I am just an average idiot and believe this.  But...
I have a 1986 Gun Digest that states otherwise.
I am not quoting from it, but I can if you guys want it.  It sources the Joint Armed Services Product Improvement Program show data results of M-855 being equal in lethality to M-193 out to 300 meters and significantly better than it past 300 meters.  So what gives?  Do we believe Fackler or US military trials?

Mortis...  

Quoted: ok, I'm confused.  Fackler states that M-193 is effective at fragmenting to 200 meters and that M-855 tops at about 150 meters.  I am just an average idiot and believe this.  But... I have a 1986 Gun Digest that states otherwise. I am not quoting from it, but I can if you guys want it.  It sources the Joint Armed Services Product Improvement Program show data results of M-855 being equal in lethality to M-193 out to 300 meters and significantly better than it past 300 meters.  So what gives?  Do we believe Fackler or US military trials? Mortis...

Dr. Fackler did the US military trials on the M193 while he was in the Army, and was involved in a Navy M855 test two years ago.  The M193 and M855 were equal out to 350 yards.

Here.  Read Tatjana's research.

www.ar15.com/forums/topic.html?id=74123

I think she's a genius or something

Saying "lethality is the same as M855 at 300 meters" is not saying "M193 fragments at 300 meters" or "M855 fragments at 300 meters."  Technically if "lethality," (a variable I have never seen measured quantitatively) was "zero" for both then they would be equal and that statement would be true.

I suppose we could measure lethality like the LD50 used in drug/toxin tests.  LS50 might be the "lethal strike in 50% of subjects."  Still, I'm way off the track now and I doubt such a variable could accurately be measured.

In short, be skeptical of any description of "lethality."  It's almost meaningless.

One other thing to remember about most of the military tests I have seen is that they don't seem to have data on the interim ranges between 100 yard/100 meter marks, e.g. 125 yards, 150 yards.  As I pointed out before all the interesting stuff happens under 200 YARDS.  After 200 yards both rounds are effectively a .22LR.  Penetration with little, if any, yaw.  At this point I think the lethality (which I hate talking about anyhow) is pretty much the same, with a slight advantage (if you think more penetration = more lethality) to the M855 because of retained velocity.

My answer to your question is that I don't totally believe either account.  I haven't been able to keep velocity of either round much above 2400fps at 200 meters from a 20" barrel much less 200 yards and I don't consider pure penetration to be a metric of lethality in isolation.  (A .177 BB penetrates pretty well at 3000fps but doesn't leave much of a wound).

To my way of thinking 5.56 rounds need to fragment at least 20% to do any serious wounding.  I don't see this happening below 2600fps.  If anyone knows of 5.56 rounds that are still above 2600fps at 300 yards (or even 200) I'd like to know about them.

Even leaving the barrel at 3250fps by 200 yards the M193 round is down to 2580 or so at 1480 feet altitude, 50% humidity, 70 degrees and 29.53 inches of mercury.

The same conditions put the round around 2250fps by 300 yards.  I don't consider that all that "lethal."

For lone operator purposes it shouldn't make a difference.  Anything over 200 yards should be a escape and evasion exercise.

I know its been a while.  I just wanted to thank you guys. AJ_Brown and brouhaha
I appreciate your info and time.  

Troy, as always, you are the man.

tatjana um.  well.  I luv ya :-)

Thanks again, Mortis...

(A .177 BB penetrates pretty well at 3000fps but doesn't leave much of a wound).

-Too cool. Where can I order mine?

I beg to differ on one small point in your post tatiana.

Quote: "after 200 yds both rounds (meaning  M193 & M855: My clarification) are effectively .22LR"

NOPE. No way.

Muzzle velocity for High Velocity Remington 36 gr. .22LR is 1280fps.  Muzzle energy is 131ft/lbs.

Velocity for 5.56mm at 500 yards (way beyond 200yds.) is about 1300fps and energy is 660ft/lbs. It ain't gonna fragment but 5.56 will penetrate far better than 22LR at any range.  

M193 and M855 are never like .22LR

Quoted: Quoted: In short, be skeptical of any description of "lethality."  It's almost meaningless. Ding ding ding!  We have a winner.   It's just like them saying "This product has been improved."  Improved how?  Compared to what?  Did the improvements in one area cause problems in others? Ballistics isn't always simple and obvious, so if you read something that makes it seem that way, you should be suspicious. Besides, many of the gun rags still quote Marshall & Sanow...   -Troy

We got these TVs at the store with "GuidePlus+Gold". No joke, two plusses there. I asked the other day "If they improve the Guide Plus again, will it be GuidePlus+Gold+?"

Scott

Quoted: I beg to differ on one small point in your post tatiana. Quote: "after 200 yds both rounds (meaning  M193 & M855: My clarification) are effectively .22LR" NOPE. No way. <snip> M193 and M855 are never like .22LR

What she means is the 5.56 will not fragment at such low velocities, thereby leaving a .22 cal hole in your target, just like a .22LR.

M193 5.56 will reliably fragment at velocities over 2700fps.  You can't get very far below that magic number before you'll basically be getting a .22cal "icepick" wound profile.

Go here to see what a M193 can do:

M193 Meets Ballistic Gel

And coming soon:  Multiple rounds of M193 meet even more ballistic gel at various velocities!

I don't want to get shot with nither, nor patch anyone up who has been hit with either.

But the discussion is intresting.