I have always been lead to believe that AR rounds do yaw, but I have read recently that this is not the case and that it is just old B.S.  I would not say the source is that reliable, but they have me thinking.  Any feedback?

read ammo-oracle.com

What does your paper target say?

Yes is the short answer . Really , Really.Though the new set -up 1/7 , 62g is engineered to be more stable .

There is no "short" answer. The 5.56mm round DOES NOT tumble. I don't care what you learned in basic, it was BS.

Not that Im aware of, how ever...did hear   1/12 twist does tumble after hitting  object.

TG

But I saw it on the History channel!

not all ammo has the same ballistics.    I did some tests with 55gr fmj Wolf, Barnaul 55gr JHP, and Olympic M855.    The Wolf & Barnaul didn't do all that much but make neat little hole.    The M855 did infact tumble and fragment.

It's a myth....

When the 5.56mm round was origionaly desighned it had little to do with balistics, the 2 main reasons the round was adopted were so that a soldier could carry more ammo, and high velocity rounds work better against armor....  However the started to notice that it seemed unusually effective, and they had no idea the reason they figured .22 caliber equals tiny hole and thats it thats one of the reasons the millitary was reluctant to switch from the M-14, so they started theorizeing on why the small round was so effective, and one of the early theorys was it must be tumbleing, however that was quickly disproven as they figured out what was really going on however the myth of the tumbling bullet persists....

What really happens is the bullet begins to yaw and the stresses become to great and it starts to spin apart, and the bullet breaks at the cannelure, the bullet nose, and the back end of the bullet both take a seperate tragectory, and as there doing that there continueing to break up, and bits of lead start to get squeezed out and each fragment in turn takes it's own seperate tragectory, in short it's kind of like a little shotgun going off inside the target....

http://www.ammo-oracle.com/images/M193.jpg

http://www.ammo-oracle.com/images/m193frag.jpg

http://www.ammo-oracle.com/images/77grMKing.jpg

Some 5.56, and .223 bullets do tumble however not be virtue of there desighn but because they were used in the wrong barrel, a classic example would be the M855, used in an M-16A1 the bullet doesn't have time to stabolize so it starts to tumble, past 100 yards it's virtually impossible to hit the target, and at 100 yards your group will be a couple of feet, and you'll have keyholes, this serves to perpetuate the myth of the tumbling bullet....

http://www.ammo-oracle.com/images/M193M855Impact.jpg

http://www.ammo-oracle.com/images/target2.jpg

I base info in the following three paragraphs on a 1986 article by Jim Sullivan of Armalite Div of Fairchild, "An Interesting Twist", in a special issue of SWAT magazine dedicated to the M16/AR-15.

The 55 gr fmj (M193) did not tumble through the air with the original 1 turn in 14" twist.  It did yaw almost immediately, according to Jim Sullivan, upon entering flesh.  With the 1:14 twist, it was just barely stabilized.

The twist was increased with the introduction of the M16A1 to 1 turn in 12".  The bullet traveled slightly farther in to flesh before beginning to yaw.

It was this yawing that was called "tumbling", and many misinterpreted this to mean the bullet tumbled through the air.  It did not.

Of course, the later faster twists, 1:7 for the A2, 1:9 for many AR-15's, and even 1:10, all stabilize M855 62 gr bullets (as well as M193 55 gr).  However, in the slower M16A1's 1:12 twist the 62 gr was not stabilized.

This caused problems during the months leading up to Desert Storm.  Some Nat Guard troops were still equipped with older A1's with the slow 1:12 twist, and M855 62gr bullets were not stabilized, would keyhole in targets.  Their rifles had to be replaced with newer A2's.

Jarhead,
I think it would be quit obvious to me, or anyone else that owns an AR or any rifle for that matter, that I wasn't referring to what the bullet does before it hits the target.

Thanks for the feedback everyone.

Only if you put it in a tumbler. I heard this myth also years ago and it is still believed by people. However It was proven to me in Marine Corps boot camp when we were shooting at 500 yds with iron sights and making hits were we aimed! A tumbling bullet would probably not even go 500 yds much less in a straight line. Also the holes were round not oval or looked like a bullet going sideways. Hope this helps. Take care.

Quoted: Jarhead, I think it would be quit obvious to me, or anyone else that owns an AR or any rifle for that matter, that I wasn't referring to what the bullet does before it hits the target.

I reread the title and original post, it was not obvious to me.  

Freeman,
I guess I didn't make it clear that I own an AR and did not expect the rounds to fly through the air sideways.  However, I had no idea people actually believed this could ever be normal and that this had been addressed in the past.  If I see marks on my targets that hit sideways I would assume I had serious troubles with my ammo or rifle and would stop shooting immediately.  

My point to jarhead was if you own a rifle and shoot on a somewhat regular occassion, you would know that if the round does not make a round hole you've got issues.  My mistake, but thanks again for everyones' feedback.  

I'll tumble for ya...

That's some funny shit!!!