Do 5.56 fmj often break up when they hit flesh or water?

[44 AMP]

I don't know if those properties were reduced so much as altered to be closer to what other larger, heavier slugs do. Still yaw and tip just not doing it until after exiting the body.

Flesh is not uniform, impact angles are not uniform, bullets always get some degree of upset from impact and passing through flesh. Tumbling while still inside a body makes bigger wounds. Tumbling after exit happens but has no effect on the wound size.

 

[Mongo_Bongo]

I don't know if they break up or not, but do know that 1969 issue M193 will get the job done.

 

[gwpercle]

No ... from experience ... shooting water jugs .
5.56 fmj ( Full Metal Jacket ) do not break up . The full jacket holds the lead core in place and they do not mushroom or break into pieces .
We had a lot of military surplus ammo that was cheap and we would shoot the ammo at water jugs , sand banks , boxes of water soaked newspaper...just to see what it would do and for the empty brass for reloading .
Gary

 

[JustJake]

Don’t know if by “break up,” the OP meant the well-noted “yaw” effect that occurs when a 5.56mm FMJ penetrates into a fluidous mass at full velocity, but the splitting apart (or “breaking up”) of a portion of the 5.56 projectile is a documented fact.

Lotsa dead southeast asian enemy soldiers learned that back in the 1960s and early 1970s. My Uncle Jimmy, from back in the ‘Nam, used to tell me about the mess it made of a human torso.

 

[jrothWA]

Recommend you visit the www.jouster2.comwebsite...

the originator was the Late Major Culver, USMC ret'd.

Who education was a Ballistic engineer during his career with the Corp.,

he wrote about his observations during the introduction of the M16 during the VN event.

There are good reports that need to brought to light.

 

[Jim Watson]

22 cal twist rates were 1-12" or 1-14".

I don't think there is any "or" to it.
The standard twist for the .222 and .222 Magnum is 14".
It sticks in my head that they made some ARs at 14" but went to 12" to stabilize a boattail bullet in cold dense air.

 

[MarkCO]

Twist rate does have a factor in this discussion, as does impact velocity.

Way over stabilized, or unstable, hitting at high speed, yep, it is going to come apart most likely. Stable, hitting at low speed, it is most likely not going to come apart. It's a dance of the two factors, as well as the specific bullet design.

There are definate differences in gelatin and Fackler box testing where the only thing changed was the spin rate. Same with only changing the impact velocity.

The devastation with the new 8.6 Blackout (1:3 twist) pretty much makes it a solid only proposition for good terminal performance. Bullets that work well on Elk, Moose and Bear from bolt guns with 1:10 to 1:12 twists are flat out exploding on impact from the 8.6 Blackout.

 

[44 AMP]

Per Speer #11 (1987)

.222 Rem
1-14" 8 rile makers
1-16" 1 maker

.222 Rem Mag
1-12" 1 maker
1-14" 4 makers

.223 Rem
1-10" 1 maker
1-12" 5 makers
1-14" 2 makers

so, I would say that while there are common twist rates, there was no standard twist rate and each rifle maker used what they thought best.

Also remember this was back when the heaviest civilian or military bullets in common use were 62-63gr.

 

[tangolima]

I think 1-12 or 1-14 marginally stabilize 62gr bullet. With slight perturbation it will tumble.

-TL

Sent from my SM-N960U using Tapatalk

 

[Ignition Override]

No idea. This info is for entertainment only - no underlying messages here:

In "The Gun", researched and written by a former (US) Marine infantry officer, he describes that the DoD in the early 60's acquired some Human Heads to compare damage by 5.56 with 7.62x39 bullets.
Many of you know about the book.

Iirc, he stated that the DoD kept the results of the test classified.
Mybe this isn't connected to the OP's question, but I found various segments of the book interesting. Secondary sidenote: Chivers is a prize-winning writer for the NYT.

https://www.amazon.com/Gun-C-J-Chivers/dp/0743271734

 

[44 AMP]

Just FYI, I have a Win M70 in .22-250, with a 1-14" twist. That rifle shoots 55gr just under an inch, 52/53gr match/varmint bullets into 3/4" or sometimes a bit better, and the 63gr Sierra "semi spitzer" into about 2"-2.5" groups.

Since that Sierra bullet is the "deer bullet" of its era, and I got some in a trade, I did test some to see how they did. Adequate groups for deer but no where near the rifle's potential with varmint bullets.

Since no .22 CF is legal for deer where I live, I've never used those slugs on deer, and have no plans to.

 

[HiBC]

With your 22-250, two factors at play
1) Velocity. Ultimately, the twist gets you RPM . RPM gets you gyro stability.
More velocity serves much like tighter twist. For a heavier bullet,a .222 will need a tighter twist than a 22-250.

Nearly all 22 centerfires were developed for light bullets a screaming high velocities, Over Mach 3 sells. 12 or 14 twist and 40 gr bullets,

2) Twist is really about bullet length,rather than weight, A VLD boat tail will require tighter twist than a flat base semi-spitzer.
(FWIW, this somewhat explains the 257 Roberts 117 round nose factory load,)