Perfect stability factor

Mikecr

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Aug 10, 2003
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NC, oceanfront
My first contention with this: Fully stable is just that. There is no more stability than that.

Also, many people get completely lost about gyroscopic stability -when they see it from an RPM perspective.
RPM is revolution per TIME.
Sg is displacement per revolution. There is no time in the parameter.
Each revolution gyroscopically counters over turning moments in a given displacement.
Displacement is relative to what is displaced (like an amount of air density), and the error moments are relative to a bullet's reactions -to displacement. For instance, drag is a bullet's reaction to air density. Bullet errors from true flight, perhaps due to marginal stability, increase drag. And BC drops with lower stability (itself).
It's easy to show examples of RPM notions failing stability tests, but I got stuff to do today.

One other thing; bullets can't be gyroscopically stable at 100yds while NOT gyroscopically stable at 600yds.
It doesn't work that way. We can't make it work that way. It isn't happening.
 

Tiny Tim

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Joined
Jan 26, 2015
Messages
476
I know that velocity decreases much fuster than spin.
I know that bullet makers have thighter twist barrels to test with reduced load (simulated long range shoots).

But I dont understand how bullet can became more stable if they lose speed.
I have seen few rifles which shoot good and straight on 100 but on 600 they keyhooled and grouping is much bigger.

I believe its is due to dynamic stability (or instability). There is a difference between gyroscopic stability and dynamic stability. Here's an article explaining the latter.

 

MOOSE39465

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LRH Team Member
Joined
Nov 11, 2010
Messages
478
Location
Petal, Ms
I dont know what custom dies have to do with throat and bullets, it all about how your brass fits, never had them ask me what bullet or throat I have when I ordered custom dies.
Still learn tryig
My first contention with this: Fully stable is just that. There is no more stability than that.

Also, many people get completely lost about gyroscopic stability -when they see it from an RPM perspective.
RPM is revolution per TIME.
Sg is displacement per revolution. There is no time in the parameter.
Each revolution gyroscopically counters over turning moments in a given displacement.
Displacement is relative to what is displaced (like an amount of air density), and the error moments are relative to a bullet's reactions -to displacement. For instance, drag is a bullet's reaction to air density. Bullet errors from true flight, perhaps due to marginal stability, increase drag. And BC drops with lower stability (itself).
It's easy to show examples of RPM notions failing stability tests, but I got stuff to do today.

One other thing; bullets can't be gyroscopically stable at 100yds while NOT gyroscopically stable at 600yds.
It doesn't work that way. We can't make it work that way. It isn't happening.
Im gonna need to study up on this. I will admit your way over my head. 😁
 

Pro2A

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Joined
May 23, 2009
Messages
229
Good evening everyone. After spending tons of money on bullets, and only coming up with marginal accuracy i'm constantly scratching my head as to why a certain bullet shoots better then others. I understand barrel harmonics along with proper bullet stability, and many other things determines accuracy. My question is what is the perfect stability factor for a given bullet? I read that an SG of 1.5 or greater is acceptable for proper bullet stability, but there's got to be a sweet spot above an SG of 1.5 that is optimum. Whats your thoughts?
There will be a lot of great input and theories, and probably a little BS for flavoring, offered below. Rolling them all together, Consistency is King. Deviation, variations will drive one mad chasing accuracy and precision. One can adjust, allow for any feature if there is consistency.
 

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