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9/22/2017 12:11:25 AM
Posted: 10/1/2005 9:32:07 PM EDT
.. I have been told that 1:9 Twist Rate will shoot bullets above 165 just as good as a 1:7 Twist Rate?
I know that on the range, it seems that alot of people use 1:7 with bullets ranging from 165 -175's......?

RANGE: 100-400 Yards - Twist Rate Recommended?

RANGE: 600-800 Yards (Bullet weight - 165-175 - Twist Rate recommended?)

Just asking for some advice?

Thanks, szst8h
Link Posted: 10/1/2005 9:45:51 PM EDT
what caliber? what diamiter bullet?
Link Posted: 10/1/2005 10:06:58 PM EDT
Sorry, 223

Thanks,
szst8h
Link Posted: 10/1/2005 10:12:09 PM EDT
Do you mean 65-75 grain bullets? There is no such thing as .224 165-175 grain bullets...
Link Posted: 10/1/2005 10:12:28 PM EDT
Ok the 223/5.56 does not use bullets of 165 or 175 grains in weight. Those are more like 308 dia. bullets?
better check out what you are asking about then respond later
Link Posted: 10/1/2005 10:14:35 PM EDT
[Last Edit: 10/1/2005 10:15:13 PM EDT by ALPHAGHOST]

Originally Posted By CaptSchofield:
Ok the 223/5.56 does not use bullets of 165 or 175 grains in weight. Those are more like 308 dia. bullets?
better check out what you are asking about then respond later



+1



www.ammo-oracle.com
Link Posted: 10/1/2005 10:33:11 PM EDT
[Last Edit: 10/1/2005 10:41:04 PM EDT by theshootersden]
The rate of twist determines the optimum bullet weight for a given caliber and speed of the bullet by applying the proper spin on the bullet to prevent the bullet form yawing and pitching. Expressed in terms of the number of revolutions per inch of barrel length, this ratio is commonly expressed by designations such as 1:9, 1/9 or 1 in 9 twist, the 1 represents 1 twist, the 9 represents inches of barrel length...

A good rule of thumb is that the heavier and longer a bullet is, the faster the twist rate needs to be to stabilize it in flight, therefore a lighter shorter bullet needs a slower twist rate to give proper bullet spin for correct flight...

Over stabilization of bullets can occur when larger heavier bullets in a given caliber are fired at very high velocities...

In general for the .223:
1x7 Good twist for the 50-80 grain bullets. Excellent accuracy with 60 grain bullets and up...
1x8 Good twist for the 50-80 grain bullets. Excellent accuracy with 55 grain bullets and up...
1x9 Good all around twist ratio. Will shoot well with bullets anywhere from 40-75 grains in weight...
1x10 Good twist for the 40-62 grain bullets, but favoring the lighter side a little more...
1x12 Good twist for the 40-55 grain bullets...
1x14 Good twist for the 40-45 grain bullets...


You can use the Greenhill formula to determine the proper bullet to twist ratio... It is based on the rule that the twist required in calibers equals 150 divided by the length of the bullet in calibers... This can be simplified to:

Twist = 150 X D2/L (The D2 is D squared)

Where:
D = bullet diameter in inches
L= bullet length in inches
150 = a constant

This formula had limitations, but worked well up to and in the vicinity of about 1,800 f.p.s. For higher velocities most ballistic experts suggest substituting 180 for 150 in the formula...
Link Posted: 10/2/2005 1:43:37 PM EDT
Sorry - 5.56 - 223 Caliber - Been some time since I reloaded for 223, I have been reloading 300WM for years OOOOOOOOOOPS

http://www.sierrabullets.com/index.cfm?section=bullets&page=bullets&caliberID=3

Thanks,
szst8h
Link Posted: 10/2/2005 1:44:56 PM EDT
Beer - I didn't mean 165 - BUT 65-75grain Ooops!
Link Posted: 10/5/2005 3:07:11 PM EDT
Does barrel length come into play at all?

Would a 24 inch 1:10 stabalize a heavier bullet better than a 16 inch or 20 inch 1:10 barrel?
Link Posted: 10/5/2005 4:12:46 PM EDT
No
Link Posted: 10/5/2005 4:42:24 PM EDT
[Last Edit: 10/5/2005 7:14:45 PM EDT by theshootersden]

Originally Posted By fq1234:
Does barrel length come into play at all?



Technically, yes it does, but its nothing that you need to consider with a battle rifle...

If your building a target/competition rifle, then you would want to do some home work before doing your build...

The length of the rifle barrel has a direct influence on the velocity obtained from the cartridge for which it is chambered along with maintaining minimal "whip"... By selecting the correct barrel length, weight and twist ratio you can fine tune the way the bullet exits the muzzle to create the perfect barrel needed for SUB-MOA accuracy...

A barrel with a faster twist will cause the bullet to exit the barrel earlier than a bullet launched from a slower twist barrel...

AVERAGE VELOCITY BULLET... Possibly the sweet spot occurs when the bullet, with the average velocity, for a particular load, exits the barrel just before the peak of its upward swing…

FASTER BULLET... A faster bullet will exit the barrel earlier and exit slightly before the average velocity bullet and the angle of the upward swing of the barrel will be slightly less. So the bullet's launch angle is slightly less, but the bullet is going faster and drops less…

SLOWER BULLET... A slower bullet will exit later and the barrel's vertical swing will be higher and at a steeper angle when the slower bullet exits. The bullet is launched at a higher angle but is slower and will drop slightly more…

The harmonics of a barrel when being fired will cause the bullet to have an upward swing when exiting the barrel...An average velocity bullet will exit the barrel just before the peak of its upward swing. A faster bullet will exit the barrel earlier and exit slightly before an average velocity bullet thus the angle of the upward swing of the barrel will be slightly less, causing the bullets launch angle to be less also, but the bullet is going faster and drops less... A slower bullet will exit later and the barrels upward swing will be higher and at a steeper angle when the bullet exits the barrel... The bullet is launched at a higher angle but is slower and will drop slightly more...
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