Silly question dealing with twist

[FOTIS]

Theoretical:

You have a 223 rem rifle and rate of twist is 1:8 which should stabilize 75 gr bullets.

Is there anything that would not allow you to send 40 gr BT's at 3500 fps?

Just curious is there such thing as "over-stabilization"?

 

[truck driver]

Don't know, I thought that might have been a problem with my 35 Whelen AI and 200gr AB 1-12" twist. But now I think it Favor's CFE223 powder.

 

[DrMike]

It is my understanding that it is possible to "over stabilize." However, it is generally more theoretical than practical. An 8 twist in a 22 caliber barrel does not appear to be liable to over stabilize.

 

[Bbear]

I read somewhere that unless you have a significant amount of faster twist OR a significantly lower bullet weight/lenght, it doesn't effect anything.
If I remember the example it was for a rifle of some flavor with a 1-12 vs 1-7 or dropping from a 90 (95?, 100?) gr bullet down to like a 50 or less. Might have been in either a 22-250 or a 243. Just can't remember.

Old-times sucks

 

[gerry]

Theoretical:

You have a 223 rem rifle and rate of twist is 1:8 which should stabilize 75 gr bullets.

Is there anything that would not allow you to send 40 gr BT's at 3500 fps?

Just curious is there such thing as "over-stabilization"?

My understanding is with a bullet like the BT and it's tough solid base it's not an issue at all. The only place it might matter would be a very light jacketed bullet, years ago you heard of some bullets in fast rounds like the 22-250 or 220 Swift vaporizing after leaving the bore. Not many bullets like that these days. I would rather have too much twist than not have enough that's for sure.

 

[Ridgerunner665]

According to Bryan Litz... Over stabilization of rifle bullets is a myth.

It started way back when they were testing heavy artillery projectiles...a 2700 pound projectile from the old 16" guns can be over stabilized, rifle bullets, however, are not fired at steep enough angles to be effected by it.

Bryan explains it very clearly in his books.

As was said though, a really fast twist in a high stepping round can and will shred thin jacketed bullets.....poof....a few feet out of the muzzle.

1 in 8" is about all I'd ever want in a high intensity hunting round... Be it a 6.5 or 7mm.

Honestly, 1 in 8.5" is all you'd ever need in a 7mm... that would stabilize the new Berger 195 grain Elite Hunter bullet, even in a 280 Ackley.

 

[Guy Miner]

Theoretical:

You have a 223 rem rifle and rate of twist is 1:8 which should stabilize 75 gr bullets.

Is there anything that would not allow you to send 40 gr BT's at 3500 fps?

Just curious is there such thing as "over-stabilization"?

My understanding is with a bullet like the BT and it's tough solid base it's not an issue at all. The only place it might matter would be a very light jacketed bullet, years ago you heard of some bullets in fast rounds like the 22-250 or 220 Swift vaporizing after leaving the bore. Not many bullets like that these days. I would rather have too much twist than not have enough that's for sure.

Used to see this, not infrequently, 15 years or so ago when target shooters were switching to faster twist barrels. Some of the bullets available, and commonly used in competition, couldn't handle the fast twist & high velocity and literally came apart mid-air. There would be a "puff" of gray/blue well out in front of the rifle, and nothing of that bullet would ever hit the target!

But, that's not the same thing as over-stabilization, which I've never seen.

Regards, Guy

 

[preacher]

I wonder, will a 1 in 8" twist overstabilize bullets in a 338/06? It was abarrel intended for the Lapua, my friend now just wants another 338/06.

 

[Ridgerunner665]

I wonder, will a 1 in 8" twist overstabilize bullets in a 338/06? It was abarrel intended for the Lapua, my friend now just wants another 338/06.

Nope...

It would enable the 338/06 to use all those big heavy bullets.

 

[jimbires]

the only thing I can think of with a faster twist would be more spin drift . I'm not sure on this , it's just my thinking .

 

[Ridgerunner665]

Not necessarily...

Up until just a few weeks ago I would have agreed with you.... But my 280 Ackley is either defying physics, or there is more to it than meets the eye.

For over 20 years (before ballistic solvers) I have always dialed 1 click (.25 moa) per 500 yards, and with the 308 and 300 Win Mag I was shooting back then, both 1 in 10 twist.... That worked.

But my 280 Ackley with its 1 in 9 twist doesn't need that click until you're past 650 yards, and that one click is all it needs until you get past 850.

Based on that, one might argue that bullet diameter has more to do with it than rate of spin.

That is range verified....I don't exactly know the physics of it, but that's what seems to be happening with my rifle.

 

[jimbires]

Not necessarily...

Up until just a few weeks ago I would have agreed with you.... But my 280 Ackley is either defying physics, or there is more to it than meets the eye.

For over 20 years (before ballistic solvers) I have always dialed 1 click (.25 moa) per 500 yards, and with the 308 and 300 Win Mag I was shooting back then, both 1 in 10 twist.... That worked.

But my 280 Ackley with its 1 in 9 twist doesn't need that click until you're past 650 yards, and that one click is all it needs until you get past 850.

Based on that, one might argue that bullet diameter has more to do with it than rate of spin.

That is range verified....I don't exactly know the physics of it, but that's what seems to be happening with my rifle.

Thanks for the info . this is something to ponder on .

 

[sask boy]

Thanks guys for the informative post :wink:! I really enjoy reading this stuff and then trying to research it .

Blessings,
Dan

 

[RiverRider]

Back when there was a confirmed new record sniper kill at some ridiculous range---something like 3000 meters, I did a little fiddling around to get an idea whether overstabilization would have affected the shot. If I recall correctly, the muzzle would have had to be elevated about 5 to 6 degrees or so. I concluded that overstabilization would have ruined the shot if the bullet had remained in its 6-degree nose high attitude the entire flight. What I have never been able to determine is what rate of twist would be required to overstabilize, and I don't know where to even begin finding that out. I can't even find information on early spin-stabilized artillery and how they learned about overstabilization and figured out what was going on.

I've spent a lot of time reading and studying stuff to try and gain an understanding how a bullet can be made to keep its rotation axis tangent to the arc of flight. When I finally put the pieces together, it was a major brain tickle. It all has to do with a small amount of "error" being managed with in a balanced manner, and I see parallels to other things I am very familiar with, such as certain electronic circuits.

Right now I am making inquiries to people with degrees in physics to find out if there is some law of physics implying that the principle is universal in systems where an equilibrium is established. I am waiting for a response from one such person right this minute.

I don't know why I gotta know this stuff, but I know I love that moment when all the pieces of the jigsaw puzzle fall into place and it all makes sense.

 

[Ridgerunner665]

As it happens, I had an acquaintance that was well versed in firing and aiming big naval guns, and the history behind it.

Another good source of info, when you can get him posting, is Bart Hobbit (BartB on the forums)... Who has a similar background as the man I once knew (now deceased).

 

[preacher]

I wonder, will a 1 in 8" twist overstabilize bullets in a 338/06? It was abarrel intended for the Lapua, my friend now just wants another 338/06.

Nope...

It would enable the 338/06 to use all those big heavy bullets.

My friend has a gob of Hornady 200sp, I told him he should be fine, after all, it isn't made like a Sierra TNT/Varminter. I was surprised just how tough that 200 Hornady is! I have another friend who uses the 338/06 and that bullet for everything from hogs to elk. I have some Speer 200s I'm trying in my 338 Federal, but mine is a stock Ruger Hawkeye. I personally feel a fast twist rifle kills a tad faster than a slow twist, on big game anyhow.

 

[257 Ackley]

Theoretical:

You have a 223 rem rifle and rate of twist is 1:8 which should stabilize 75 gr bullets.

Is there anything that would not allow you to send 40 gr BT's at 3500 fps?

Just curious is there such thing as "over-stabilization"?

My understanding is with a bullet like the BT and it's tough solid base it's not an issue at all. The only place it might matter would be a very light jacketed bullet, years ago you heard of some bullets in fast rounds like the 22-250 or 220 Swift vaporizing after leaving the bore. Not many bullets like that these days. I would rather have too much twist than not have enough that's for sure.

Used to see this, not infrequently, 15 years or so ago when target shooters were switching to faster twist barrels. Some of the bullets available, and commonly used in competition, couldn't handle the fast twist & high velocity and literally came apart mid-air. There would be a "puff" of gray/blue well out in front of the rifle, and nothing of that bullet would ever hit the target!

But, that's not the same thing as over-stabilization, which I've never seen.

Regards, Guy

Yep, this is about the only problem I see. I tried some 65 grain light jacketed bullets in a 6mm 7 twist a couple years ago and all you would see is a puff of smoke about 50 yards in front of the barrel.

 

[Whitesheep]

I've spent a lot of time reading and studying stuff to try and gain an understanding how a bullet can be made to keep its rotation axis tangent to the arc of flight. When I finally put the pieces together, it was a major brain tickle. It all has to do with a small amount of "error" being managed with in a balanced manner, and I see parallels to other things I am very familiar with, such as certain electronic circuits.

This topic intrigues me as well. I have always wondered how bullets remain "tangent to the arc of flight." I suppose it has to do with balancing aerodynamics on the projectile, but have never been able to articulate my question in the form of a usable Google search that would allow me to research further.

If you would be so kind to share some of your musings on this topic I would appreciate it. Especially if you have any sources you would recommend, including Bryan's.

 

[RiverRider]

I'll give it a shot, Whitesheep. It will take me a while to write it, find out it is confusing and sucks, rewrite it and lose it because I forgot to save it, then rewrite it once again.
Once I get my act together I'll share it right here in this thread. It sure won't be tonight, though.

 

[RiverRider]

Okay, gents...I am posting a write-up in the forum in a new thread.