Author Topic: Twist rate vs bulet weight  (Read 621 times)

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Offline Freezer

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Twist rate vs bulet weight
« on: May 28, 2008, 05:41:38 PM »
    My brothers step son inherited a Savage 99f in 300 Savage from his grand pa.  I can't find the twist rate off hand but my load data research is showing some interesting things.  First with 150 gr spbt the 300 can compete or best the 308.  The Hornaday manual lists a max charge for the; 300 with IMR 4064  44.0 gr @ 2800 fps using a 22" barrel & 1 in 12 twist
                               308 with IMR 4064  44.9 gr @ 2700 fps using a 22" barrel & 1 in 10 twist

    This said what was the twist rate for the 1958 Savage 99f?   What bullet weight is best with it's twist rate?  Would I be better looking at a 165 or 180 gr bullet or was it designed for the 150's? 

   

Offline Grumulkin

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Re: Twist rate vs bulet weight
« Reply #1 on: May 29, 2008, 01:32:33 AM »
I would have no idea what the twist rate is but...

The twist needed to stabilize a bullet is related to the velocity obtained (with faster velocity a slower twist will do) and to the bullet length (not bullet weight though that is related).  This means that a round nosed bullet would be stabilized easier than a spitzer bullet of the same weight.  For you're application, I would probably try 165 or 168 grain bullets first.  If you don't like the results, try some 150s.  If you like the results and feel the need then try either the heavier or lighter bullets.

Offline Val

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Re: Twist rate vs bulet weight
« Reply #2 on: May 29, 2008, 05:46:25 AM »
I just developed a load for my Model 99 in 300 Savage using Hornady 130 grain SPs. I wanted a faster muzzle velocity.The load Chronographs at 2789 fps. I'm using 43.5 grains of Varget with Winchester WLR primers. I was going to try some IMR 4064 but the powder wouldn't fit in the casing without an overflow.
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Offline coyotejoe

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Re: Twist rate vs bulet weight
« Reply #3 on: May 31, 2008, 03:48:10 AM »
Don't know the twist rate but the cartridge was originally introduced with a 150 grain bullet and the older Savage action was quite short, it had to be modified a bit to handle the .308. The round has such a short neck that combined with a short action length, any longer bullets would have to be seated deeply below the case shoulder. If I were loading the .300 with 180 grain bullets they would be roundnoses to keep the overall cartridge length short enough to feed.
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Offline Castaway

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Re: Twist rate vs bulet weight
« Reply #4 on: May 31, 2008, 11:43:16 PM »
To figure your twist, take a swivel cleaning rod, make an index mark towards the top, place a patch on the bottom and run it though the barrel.  Note the position of your mark, when it makes one revoloution, measure the distance traveled down the barrel.

Offline PaulS

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Re: Twist rate vs bulet weight
« Reply #5 on: June 02, 2008, 11:10:28 PM »
The longer the bullet is the faster the rifling twist has to be.
a pistol bullet at 180 grains in 35 caliber uses rifling that is almost half of the twist in a 27 with a 180 grain bullet.
The speed of the bullet has little to do with the stabilizing ability of any twist rate. The 6mm Remington proved that. Even at the velocities used in the 6mm the longer bullets would not stabilize. I don't think you can get too fast a twist rate for a bullet and i proved that to myself shooting a 158 grain pistol bullet at 2500+fps from my 358 Winchester. Grouped sub-caliber continuously. I almost hated to shoot rifle bullets after that. (1:12 twist)
PaulS

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