Winchester 64gr Power Point ammo

[ScottR]

What was this round developed for? I know allot of 40gr to 55gr are varmint rounds, 64gr more for deer?
Any one shoot these out of there AR?

Just curious, thanks.

Scott

Information

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[jjroth]

those jurisdictions that allow .22 centerfire catridges.

[Bill F]

Could someone clue me in to the 55 gr.bullets in the pre-ban AR 15.Is it the barrel twist?TIA

[jjroth]

was a 55gr bullet, which dou to weight required a faster twist, which was the 1:12,
(mean one complete revolution in a 12 ' long distance.

With the use of the 62gr enhanced penetration cartridge, the weight increase dictated a faster twist: 1:7.5".

There's a specfic formula that determines the twist, I don't have it.

[limazulu]

HOW TO CHOOSE THE PROPER RIFLING TWIST RATE
By Norm Johnson
The Greenhill formula is an empirical equation that does a good job of establishing the barrel twist necessary so that a bullet of a given length will be adequately stabilized.
Greenhill made easy:
T=(150 x D)/R
where:
T is the twist required (number of inches for one revolution),
D is the bullet diameter (in inches)
R is the bullet length to diameter ratio, (length divided by diameter)

Conversely, to find out what length bullet will be stabilized in a given twist, use:
L=(150 x D x D)/T
(that is, 150 x D squared divided by T)
where:
L= bullet length
The number 150 is a constant used by Greenhill and works well at velocities in the vicinity of 1500 fps or greater. At 2800 fps the constant can be changed to 180 with good results.
Note that it is bullet LENGTH, not weight that is important. Greenhill works well with all lead/lead-alloys commonly used for bullets.
One must understand that Greenhill is derived from experience as well as from the calculated laws of physics. As such, it is a highly simplified, albeit useful, equation. Greenhill was worked out many years ago and is quoted in the British Textbook of Small Arms (1929).

[hagar in SC]

I shot many 100's of these out of a 1 in 14 twist 22/250, and many more out of a Mini-14. They killed coyotes like the hammer of Thor, and I also shot 2 deer and a Javelina with them. They mushroom well, and don't go to pieces. It turned the Mini into a moa shooter, and I shot some of the best groups ever out of my 22/250, 5 shots at 100 yards smaller than a dime. Have done some limited testing with them out of an Ar, and they shoot well. I have an unopened case of 2000 that might be used for highpower shooting if these ridiculous component prices don't come down soon.