Do 5.56 fmj often break up when they hit flesh or water? - Page 2

Jim Watson · April 25, 2023, 11:38 PM

Quote:

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 · April 26, 2023, 11:13 AM

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** · April 26, 2023, 12:52 PM

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 · April 26, 2023, 11:35 PM

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 · May 25, 2023, 03:26 PM

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** · May 25, 2023, 04:51 PM

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 · May 25, 2023, 07:28 PM

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,)

April 26, 2023, 11:13 AM	#27
MarkCO Senior Member Join Date: October 21, 1998 Location: Colorado, USA Posts: 4,109	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. __________________ Good Shooting, MarkCO www.CarbonArms.us

April 26, 2023, 12:52 PM	#28
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 27,785	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. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

May 25, 2023, 03:26 PM	#30
Ignition Override Senior Member Join Date: February 18, 2008 Location: About 20 nm from the Big Muddy Posts: 2,848	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 Last edited by Ignition Override; May 25, 2023 at 04:38 PM.

May 25, 2023, 04:51 PM	#31
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 27,785	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. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

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April 26, 2023, 11:35 PM	#29
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,443	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

May 25, 2023, 07:28 PM	#32
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,184	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,)