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Schmo

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Have yet to shoot the 80s yet, so we’ll see. I know what velocity bracket I’ll be in though from other loads I’ve run. Should be 2900 - 3000. The 80 ELD-M box says 7 twist, but the website says 8 twist. Anyone know what stability number is safe? Is it anything over 1?
 
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Have yet to shoot the 80s yet, so we’ll see. I know what velocity bracket I’ll be in though from other loads I’ve run. Should be 2900 - 3000. The 80 ELD-M box says 7 twist, but the website says 8 twist. Anyone know what stability number is safe? Is it anything over 1?

I got this from another forum years ago.

IMG_0644.png

80 gr in a 1-8” is on the edge, might not be suitable for long range. Stability decreases with velocity loss.




P
 
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Berger stabilizer program says marginally stable at 3000 fps at 2000’ elevation.

1.160”, .244 G7, SG 1.23

My load is also “marginally stable” at 1.33 but it shoots very well out to 500 yards.
 

Marbles

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Have yet to shoot the 80s yet, so we’ll see. I know what velocity bracket I’ll be in though from other loads I’ve run. Should be 2900 - 3000. The 80 ELD-M box says 7 twist, but the website says 8 twist. Anyone know what stability number is safe? Is it anything over 1?
Depends. Bare muzzle, just try it and see. Using a can, technically 1 or more, but I personally would want some wiggle room for changes in atmosphere and lower velocity rounds.
 

Schmo

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Hornady 4DOF lists my muzzle stability at 1.22 for my elevation. I’m at 1,230’ above sea level. Highly unlikely that I’ll shoot or hunt at anything lower than 900’. Most is done either at my elevation, or 3,000’ - 6,000’.

Stability decreases with velocity loss.

4DOF shows the opposite. Because rotation does not decrease near as rapidly as velocity. See attached picture where it shows gyroscopic stability increases with range.

IMG_4101.png
 

Marbles

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Hornady 4DOF lists my muzzle stability at 1.22 for my elevation. I’m at 1,230’ above sea level. Highly unlikely that I’ll shoot or hunt at anything lower than 900’. Most is done either at my elevation, or 3,000’ - 6,000’.



4DOF shows the opposite. Because rotation does not decrease near as rapidly as velocity. See attached picture where it shows gyroscopic stability increases with range.

View attachment 798601
I think you two are talking about different things.

As muzzle velocity goes down, so does RPM.

However, once a bullet has whatever RPM it has leaving the barrel, it holds on to that RPM better than it does velocity.
 

Schmo

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However, once a bullet has whatever RPM it has leaving the barrel, it holds on to that RPM better than it does velocity.
Yes, exactly what I said. The RPM doesn’t drop near as fast as velocity does. So it becomes more stable, not less. Correct?
 

Marbles

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Yes, exactly what I said. The RPM doesn’t drop near as fast as velocity does. So it becomes more stable, not less. Correct?
Sorry, I had a brain fart, clearly the post you quoted referenced velocity loss down range, so my point is wrong.

I don't know enough to say if stability gets better or worse down range prior to going transonic. I am under the impression that if stable at the muzzle, it will remain stable down range.

Anyway, sorry for jumping in so fast I apparently only half read things at first.
 

Schmo

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It’s all good! Guess I’ll just shoot some and see!
 
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