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Re: Accuracy Problems [message #35502 is a reply to message #35500] Thu, 08 January 2015 11:25 Go to previous messageGo to next message
jamesgammel is currently offline  jamesgammel
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don't kid yourself it's already HERE.
Jim

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Re: Accuracy Problems [message #35505 is a reply to message #35485] Thu, 08 January 2015 12:03 Go to previous messageGo to next message
Brian Pfleuger is currently offline  Brian Pfleuger
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rchatting wrote on Thu, 08 January 2015 06:43
Isn't stability more a function of the bullet length and not necessarily the speed of that bullet? So the twist matches the typical length of the bullet so case is irrelevant?



The required RPM is a function of bullet length, yes, but getting that RPM only has two variables.... barrel twist rate and velocity. Since the twist rate is fixed (in a given barrel), the required RPM can only be achieved with more velocity.

[Updated on: Thu, 08 January 2015 12:04]

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Re: Accuracy Problems [message #35538 is a reply to message #35505] Thu, 08 January 2015 22:31 Go to previous messageGo to next message
rchatting is currently offline  rchatting
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Brian Pfleuger wrote on Thu, 08 January 2015 12:03
rchatting wrote on Thu, 08 January 2015 06:43
Isn't stability more a function of the bullet length and not necessarily the speed of that bullet? So the twist matches the typical length of the bullet so case is irrelevant?



The required RPM is a function of bullet length, yes, but getting that RPM only has two variables.... barrel twist rate and velocity. Since the twist rate is fixed (in a given barrel), the required RPM can only be achieved with more velocity.


I guess I didn't word that correctly. The velocity is a factor, but if I remember from playing around with the Miller formula, the bullet length had a much greater effect on the recommended twist rate. I think a .308 at 2700 was pretty close to the same as 2300 fps as for recommended twist.

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Re: Accuracy Problems [message #35549 is a reply to message #35538] Fri, 09 January 2015 11:49 Go to previous messageGo to next message
Brian Pfleuger is currently offline  Brian Pfleuger
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Yes, length has the greatest effect because it dictates the lever-arm (leverage) of the oncoming air which is trying to tip the bullet.

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Re: Accuracy Problems [message #35614 is a reply to message #35549] Sat, 10 January 2015 20:30 Go to previous message
Crubear is currently offline  Crubear
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My 2cents - I had a 357 max barrel (forget how long, but rifle legal) that would shoot 357 max perfectly, 357 mag so-so, and 38 special was the best shotgun group I'd never want to see. You are asking a low pressure round to jump a VERY long way to enter the throat. In that time a lot of pressure has moved around the bullet, maybe even causing a Major wobble and accuracy is going to pay.

Stability is a factor of bullet weight, velocity, and how you hold your eyes when you squeeze the trigger

Honestly, I have all the barrels I want or could ever need..... wait, look, there's another!!

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