Twist relation to accuracy/velocity node

BoomFlop

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So I just started reloading and just recently shot a load work up in 2 different 223 Rem bolt guns.

20" bolt gun with 1-9tw had great accuracy of .28" at 100 yards but was in the middle of the charge range. RPM of let's say 288,000.

26" bolt gun with 1-12tw had decent accuracy at .59" at 100 yards around max charge range. RPM of let's say 234,500.

Is the twist causing the difference in preference of charge weight or is it just a particular rifle thing? What are your thoughts?

I wondering if I can go up a little in bullet weight and maintain the velocity as it may potentially like a closer to max charge?

Just trying to learn from what I'm seeing so I can make more accurate assessments in the future.

Thanks
Steve
 
Last edited:
Steve
RPM for a 1-9 twist @ 3000 fps would be 240,000 RPM 3000\.75 X 60 Secs=240,000 Where 9 twist is .75 Ft.
The twist rate should not have much effect on accuracy except in extremes high or low. If a Bullet is fully stabilized then it should be accurate as well. You can not over stabilize a bullet. Spinning the jacket off is another topic for another thread.
I shoot a lot of 223 to control gophers on our ranch and neighboring ranches. We load a max charge of CFE 223 and a 50gr V-Max all are 1-9 twist. We also shoot 220 Swift and load the 50gr V-Max in a 1-12 twist. The 40 gr is both a little short and light to my liking. I have had the best luck with 50-53 gr in .224 caliber.
 
Sorry, I missed a number in both numbers.

So the fact my LTR likes a middle of the range charge and my son's Varmint likes the max charge is purely just specific gun and not twist related?

my son had point of impact shifts vertically (dropped as charge weight went up), which I'm guessing the bullet leaving his 26" barrel sooner in the up swing of harmonics. My 20" barrel did not change point of impact much at all (I'm assuming stiffer barrel). That a reasonable assumption?

Thanks
Steve
 
So the fact my LTR likes a middle of the range charge and my son's Varmint likes the max charge is purely just specific gun and not twist related?
Yes that is correct.
my son had point of impact shifts vertically (dropped as charge weight went up), which I'm guessing the bullet leaving his 26" barrel sooner in the up swing of harmonics. My 20" barrel did not change point of impact much at all (I'm assuming stiffer barrel). That a reasonable assumption?
Yes that is also correct. A longer barrel will gain a bit more velocity as the powder charge goes up. Each barrel will react differently with differing inputs.
 
Both barrels are different lengths and different contours. That in itself can affect your velocity node due to harmonics. A lot of things can affect it. Neck tension and seating depth is another. Just because your groups changed with powder charge doesn't give you the full story. Work up a powder charge that provides the best consistency in velocity, and adjust accuracy with seat length.
 
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