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August 3, 2010, 11:54 AM | #1 |
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Join Date: February 2, 2010
Location: Illinois
Posts: 395
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223 Twist Rate and Terminal Ballistics
This is pertinent to me because my HD firearm is my AR 15.. so I look to get the absolute best terminal ballistics out of it.
My understanding of why 223 rounds fragment is because they yaw to about 90 degrees and the surface area exposed to the force of flesh is maximized and it breaks apart under the pressure. So if the bullet needs to yaw in order to fragment, what causes it to yaw? Flesh is quite a bit denser than air, so when the bullet impacts the spin rate slows drastically and then the center of gravity in the rear of the spitzer-style bullet swings forward. It makes sense to me that if you use a slower twist (1:9) as opposed to faster (1:7), the round will slow down faster in flesh and therefore begin to yaw in a shorter distance after impact, thereby increasing the terminal effectiveness of the round. Am I wrong?
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August 3, 2010, 12:02 PM | #2 |
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Join Date: June 14, 2004
Location: NY State
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Instead of wearing yourself out with numbers , it might not be significant at HD range. Instead get the Federal 40 gr load which will penetrate less than any other load so it's better th for HD and it will do the job.
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August 3, 2010, 02:15 PM | #3 | |
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Join Date: June 12, 2000
Location: Texas and Oklahoma area
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Quote:
See this: http://www.razoreye.net/mirror/ammo-...r.htm#twistduh for a more detailed explanation. Also remember that yawing more quickly, while generally a good thing, isn't always a plus if it reduces penetration past a certain point (for example a .223 40gr HP). There are a lot of factors that can affect bullet performance and many of them are factors you don't have much control over. Luckily, the most important factor is also the one you have the most control over - shot placement. |
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August 3, 2010, 02:18 PM | #4 |
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Join Date: May 12, 2010
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You want rapid expansion for HD. 55gr HP's are a good compromise for penetration and rapid expansion.
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August 3, 2010, 06:40 PM | #5 |
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Join Date: February 2, 2010
Location: Illinois
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That is a very useful link, Bart. Consider the questions answered in full
Thanks a lot, fellas.
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Tags |
ballistics , rate , terminal , twist |
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