As time goes on more and more "experts" in the field of ballistics are coming out about how over-stabilization of a bullet is a myth and only a little tiny tad right.

Bryan Litz, the ballistician at Berger Bullets and a member of the U.S. Palma team, published his book Advanced Ballistics for Long-RangeShooting. Bryan’s research involved a lot of shooting and calculating He has a degree in aeronautical engineering.), and the book included interesting stuff about bullet stabilization. Bryan wrote that there’s a tiny particle of truth to the notion of overstabilization, but the effects have been greatly exaggerated. He cited various examples showing that with a well-balanced target bullet the effect is so small it can’t be seen in 1,000-yard shooting. Here again it should be stressed that Bryan’s information is based on extensive shooting to determine the way bullets actually fly, including realistic ballistic coefficients. The home page of his website, www.appliedballisticsllc.com, has a quote from Yogi Berra: “In theory there is no difference be-
tween theory and practice. But in practice, there is.” Any real rifle loony should own a copy of Ad-
vanced Ballistics, partly because it comes with a CD of Bryan’s computer ballistics program. A second
edition appeared in 2011, containing the tested ballistic coefficients for a lot more bullets. Despite all this evidence, some supposed professionals still dread the possibility of overstabilization. Toward the end of my .260 experiments, I ordered another custom rifle in 7x57mm Mauser from a different maker. The gunsmith asked what bullet I’d be shooting most, and I said Nosler 140-grain Partitions or Ballistic Tips, assuming he asked because we’d discussed using a special reamer with a short throat.
The rifle shot both bullets very well, but one day I decided to try the new Swift 150-grain Scirocco. It wouldn’t group better than 2 to 3 inches at 100 yards, and Sciroccos had shot much better in other
rifles. I became curious and measured the rifling twist by using a cleaning rod to push a tight bore
brush wrapped in a dry cleaning patch through the barrel. The twist turned out to be one turn in
11.5 inches, evidently what the gunsmith considered ideal for 140-grain Noslers. (In fact, if you run
the 140 Ballistic Tip at 2,900 fps through the Sierra Infinity twist-rate program, it comes up with an
11.5-inch twist.) Interestingly, I’d previously owned another 7x57 with a 9-inch twist (pretty much
standard for 7mm barrels) that shot 140-grain Noslers into even smaller groups. In fact five-shot
groups often measured .5 inch at 100 yards, even with the supposedly inaccurate Partition.
Believe it or not, like a big dummy I somehow got talked into trading that 7x57 and three boxes of 140
Partition handloads to a guy who shot up all the ammunition on prairie dogs simply because the
rifle shot so well. Then he wanted me to load him some more. At least I didn’t fall for that. In fact, a
rifling twist just enough to stabilize a bullet causes far more problems than the nonexistent tragedy
of overstabilization. Aside from the Sierra program, numerous other twist-prediction formulas
exist, from the original 1879 Greenhill Formula to the sophisticated formula Bryan Litz includes in his
CD, devised by my friend Don Miller. I first met Don at the SHOT Show several years ago, where he
Showed me some complicated computations proving why my empirically devised 4-to-1 powder-capacity formula actually works. In Don’s twist formula, the minimum twist required to stabilize a specific bullet is expressed as an Sg (stability factor) of 1.0. However, bullets fired in a 1.0 Sg twist, or even a 1.1 or 1.2, will wobble very slightly. Unlike overstabilization, this really does reduce accuracy and ballistic coefficient (BC). Also, even the BC of a really stable bullet varies with different
conditions, including air density temperature and humidity. Dense air decreases BC, whether the
density is due to lower elevation temperature or humidity. Hydrogen molecules weigh less than
carbon or oxygen molecules, so more H2O in the atmosphere reduces density. The same three factors also affect bullet stability. If a bullet barely stabilizes at 70 degrees just after a July rain in the Montana mountains, it won’t stabilize at all on a cold, dry November day on eastern Montana’s plains. Some margin of overstabilization actually helps maintain accuracy under varying environmental conditions. Litz suggests an Sg of at least 1.4, as calculated with the Miller formula. The Sierra Infinity program calculates twist rate for a 1.25 Sg, but the results of the Miller and Sierra formulas can vary considerably, partly because the Sierra formula doesn’t include environmental factors – or at least my version doesn’t. Many shooters mistakenly believe bullet weight is the only factor in rifling twist. In reality bullet length is the major factor, with overall shape a second influence. This is why Barnes doesn’t make a .35-caliber bullet heavier than 225 grains: A 250-grain TSX wouldn’t stabilize in the “traditional” one-in-16-inch twist found in many .35 barrels, even factory-produced .35 Whelens.
Most shooters believe extra muzzle velocity helps stabilize a bullet. Like the myth of overstabilization,
this contains a kernel of truth, but in reality extra velocity only helps a tiny amount. There are two con-
flicting factors in stabilization: the bullet’s center of gravity, determined by the rate of spin; and the
center of pressure, the force of the atmosphere on the front of the bullet, which tends to destabilize
the spinning bullet. When muzzle velocity increases, the gyroscopic stability of the bullet increases,
but the air pressure on the bullet also increases. The two forces almost counteract each other, with
a slight edge going to faster spin. I’m a big fan of .25-caliber rifles, and the standard rifling twist for
most .25-caliber centerfires is one in 10. This has proven to work for 115- to 120-grain bullets, the heaviest spitzers commonly available, but appears to be marginal for the .250 Savage, both in practice and the Miller formula. I’ve owned a bunch of .250s with 10-inch twists, both factory and custom rifles, and haven’t encountered any that shoot 115- to 120-grain spitzers as accurately as lighter bullets. In .25-caliber cartridges from the .257 Roberts on up, a 10-inch twist has proven plenty for fine accuracy even with the longest spitzers. However, an acquaintance who shoots a lot at long range claimed accuracy went to pieces beyond 600 yards when shooting the Nosler 120-grain Partition from his .257 Roberts in subzero weather. To him this suggested a 10-inch twist wasn’t enough, which brings up another myth. Many shooters believe a bullet becomes less stable as velocity drops. This also contains a kernel of truth but occurs only when the velocity drops to the transonic range of about 1,300 to 1,100 fps. As Litz explains, “Some bullets . . .will not have enough dynamic stability to survive the large swings in aerodynamic forces and torques as they fly through the punishing sound barrier.” This was exactly what happened with 120-grain Partitions in the .257 Roberts in thick winter air. It’s also the reason long-range shooters prefer bullets to stay above transonic velocity out to the longest range they’re shooting. Hunters, however, use expanding bullets that won’t open much below 2,000 fps, so rarely encounter transonic bullet instability. In fact, as long as velocity remains above the transonic range, bullet stability actually increases as velocity drops. Even the sleekest bullets lose around 5 percent of their velocity during each 100 yards of travel, so air pressure on the front of the bullet drops relatively rapidly. Meanwhile the bullet’s spin rate doesn’t decrease much at all, so as velocity drops the bullet’s center of balance gains an increasing edge in its battle with the center of pressure.
Some rifle manufacturers list twist in their specifications, but some don’t; and even in factory rifles
there can be surprises. Early .250 Savages supposedly had 14-inch twists, since the cartridge was orig-
inally designed to shoot an 87-grain spitzer. This eventually proved just enough to also stabilize a lead-core 100-grain spitzer, though just barely. I’ve also owned a bunch of 14-inch twist .250s from early Savage 99s to a Winchester Model 70 Light-weight Carbine made in the 1980s. I found they’d usually shoot either the Speer 100-grain Hot-Cor or Hornady InterLock quite well, but eventually ran into a takedown 99 that refused to cooperate. Now, some people believe take-down rifles don’t shoot as well as solid frames, but that hasn’t been my experience with most Savage 99s, so I continued to wrestle with this rifle. Eventually a light went on, and I measured the rifling twist. It turned out my nifty, old rifle had a 15-inch twist. This is easily explained: Savage barrels, and many others of the early twentieth century, were rifled on sine-bar machines. These can be infinitely adjusted to any reasonable rifling twist, but the rate of twist can vary somewhat due to the skill of the operator. I tried some Speer 87-grain Hot-Cors in my one-in-15-inch barrel, and they shot great. Since then I’ve corresponded with a guy who has an old .250-3000 99 with a one-in-13 rifling twist, so apparently the 14-inch twist was essentially a suggestion, perhaps not so closely followed on Mondays. These days most bullets are so
well balanced many rifle manufacturers have started using much faster twists in their barrels, allowing shooters greater flexibility in bullet weight and length. I recently tested a couple of .224 cen-
terfires with 8-inch twists that shot bullets as light as 40 grains into very small groups. There’s really
no reason for today’s hunters to be scared of overstabilization, or any of the other barrel-twist myths
that crop up repeatedly in sporting goods stores and hunting camps. •

Like I mentioned in a post in the fast twist AR15 thread, the only danger of overstabilization is loss of bullet integrity. All bullets experience yaw when leaving the muzzle due to muzzle blast or unsquare bases, and this wobble must be dampened by the spin in order to achieve repeatability.

That article points out two especially important points: Transonic destabilizing forces, which can actually cause an increasing helical spiral effect beyond the distance the transition occurs, and the fact that pressure on the nose decreases as velocity decays, but the rotational velocity does not significantly change, so the bullet actually becomes MORE stable the further it goes downrange (until the transonic point).

Our only limits to launching cast bullets accurately at high velocity is the strength of the alloy and our ability to get them out of the gun without ruining the concentricity of their shape.

Gear

quote:

Originally posted by Geargnasher:
Like I mentioned in a post in the fast twist AR15 thread, the only danger of overstabilization is loss of bullet integrity. All bullets experience yaw when leaving the muzzle due to muzzle blast or unsquare bases, and this wobble must be dampened by the spin in order to achieve repeatability.

That article points out two especially important points: Transonic destabilizing forces, which can actually cause an increasing helical spiral effect beyond the distance the transition occurs, and the fact that pressure on the nose decreases as velocity decays, but the rotational velocity does not significantly change, so the bullet actually becomes MORE stable the further it goes downrange (until the transonic point).

Our only limits to launching cast bullets accurately at high velocity is the strength of the alloy and our ability to get them out of the gun without ruining the concentricity of their shape.

Gear

Yup and all that BS and fighting over the BS made up rpm threshold. The blind will never see it.

The original post here is not my writing. It's from the Dec/Jan issue of Reloader magazine and John Barsness wrote the article. One could say it's his post.

1. they paid him to write that article.

and, by the way, what you have done, reprinting this article without specific permission of the author(s) is copyright infraction in most countries. That's against the law.



2. subscribers numbers are down at most publications due to lack of news to report. Controversy sells magazines.

This one reminds me of the old days where a magazine would have one staffer conjure up an article stating: the 30-06 is all you need for NA game. Next issue: the 270 is all a real rifleman needs.

Third issue: a third staffer settles it: the 280 Remington "outperforms" both.

I remember the absolute dorkiest article I ever read, by Skeeter Skelton no less. The title: "Skeeter prefers a 5" barrel; will keep his 4"s and 6".

Stabilization is a very simple issue.

Visualize the bullet from the base. It is a perfect circular outline. Quarter it with vertical and horizontal crosshairs.

That is geometric (actual) center.

Draw a dot there.

Now, due to production tolerances, draw a second dot just .00002" off center.

In this case, that is the gravitational center. Spin it to see this.

The bullet has to stay centered inside the barrel.

Once it leaves, those two centers cause wobble, due to the tremendous centrifugal forces.

Spin it fast enough, it ruptures.

It is that easy.

Cures: closer tolerances, thicker jackets, monolithic solids/HP's.

quote:

Originally posted by Idaho Sharpshooter:
1. they paid him to write that article.

and, by the way, what you have done, reprinting this article without specific permission of the author(s) is copyright infraction in most countries. That's against the law.



2. subscribers numbers are down at most publications due to lack of news to report. Controversy sells magazines.

This one reminds me of the old days where a magazine would have one staffer conjure up an article stating: the 30-06 is all you need for NA game. Next issue: the 270 is all a real rifleman needs.

Third issue: a third staffer settles it: the 280 Remington "outperforms" both.

I remember the absolute dorkiest article I ever read, by Skeeter Skelton no less. The title: "Skeeter prefers a 5" barrel; will keep his 4"s and 6".

Stabilization is a very simple issue.

Visualize the bullet from the base. It is a perfect circular outline. Quarter it with vertical and horizontal crosshairs.

That is geometric (actual) center.

Draw a dot there.

Now, due to production tolerances, draw a second dot just .00002" off center.

In this case, that is the gravitational center. Spin it to see this.

The bullet has to stay centered inside the barrel.

Once it leaves, those two centers cause wobble, due to the tremendous centrifugal forces.

Spin it fast enough, it ruptures.

It is that easy.

Cures: closer tolerances, thicker jackets, monolithic solids/HP's.

The proof is in the shooting. Mr Barsness was writing about what Litz, who has an aeronautical engineers degree and a ballistician, has discovered through actual testing. I suggest you do the testing for yourself as have a lot of us. Over spinning the bullet doesn't have that much effect on accuracy to cause the shooter a actual problem.

1. you are still a thief. Nothing except deleting your stolen intellectual property and a profuse apology will change that. Actually, that won't even work, you will then be a self-confessed thief.


2. I had, and still have, close friends at Picatinny Arsenal I talk ballistics with on a regular basis. They deal with both internal and external ballistics, about three hundred of them at last count on a billion dollar annual budget. Sierra, et al, chiseled in stone ballistics tables in their reloading manuals for going on 40 years now. They got 90% of their software from Picatinny Arsenal. A number of years ago, Sierra began showing at least three BC's, based on velocity for their match bullets. That was based on updated data/software from PA. They now call their drop tables/BC's "guidelines, and suggest, that all data be field tested. I can match about 1/3rd the time within 1-2moa.

3. you have chosen not to dispute what I wrote, which is my original data from an article I wrote for Precision Shooting Magazine more than twenty years ago. I had just enough Math & Physics in school to be able to do a simple calculation. You can test cheaply if you wish, just turn a wooden top out on your wood lathe and spin it. Spin it on your table top and watch it spin a bit, then settle down into a nice easy gyration. Put a teensy nick in the skin and watch it go "topsy-turvy"* across and off the table. It never gets to stabilize because of the external imperfection you introduced. Internal imperfections are every bit as bad, and generally miniscule.

Without having read the article, I would expect a simple phone call would elicit the information that they use a Juenke Comparator or equivalent to test each bullet, and then loaded.

4. I have a question for you: if there are any real world validity AND consistencyto the article you stole and then reprinted here, why is it that Bench Rest, the ultimate accuracy game in the world, chooses very sloooooow twists in their 6PPC's (1:14) and 30BR's (1:17). They spin their match bullets (in the barrel) just fast enough to stabilize them.

Every statement you have made, or stolen, is at odds with the reality of external ballistics.

Try making sense, just for once.

Rich

I once read, somewhere, that it easy to appear wise. Just think of something stupid to say, or in this case, post; and then don't.



*catchy phrase, that.

Rich,

I'm not arguing with you. If you want to know ALL the reasons they shoot the slow twists in benchrest as someone such as Lija or McMillan. Call them up and ask them to tell you ALL the reasons. You'll be surprised.

Not that your opening statements have any validity,but for your information that's not the whole article. Much is missing including pictures and lengthy description to the pictures.

I bought my first Lilja barrel from Dan in 1988. Still have five.

I've competed at the Super Shoot. Fred Sinclair built my first 6PPC for me himself in 1990.

I wrote for Precision Shooting Magazine for more than eleven years.

The Palma Team specifies a very specific barrel twist and interior dimensions. The rifling is designed have the bullet ride on the top of the lands.

I shot BR matches when Eunice was still alive, and active in competition. You are getting to the football game at halftime, and trying to tell me what went on based on listening to it on the radio. I was sitting there.

quote:

Originally posted by Idaho Sharpshooter:
I bought my first Lilja barrel from Dan in 1988. Still have five.

I've competed at the Super Shoot. Fred Sinclair built my first 6PPC for me himself in 1990.

I wrote for Precision Shooting Magazine for more than eleven years.

The Palma Team specifies a very specific barrel twist and interior dimensions. The rifling is designed have the bullet ride on the top of the lands.

I shot BR matches when Eunice was still alive, and active in competition. You are getting to the football game at halftime, and trying to tell me what went on based on listening to it on the radio. I was sitting there.

I'm glad you wrote that Rich. What I was told that dictates most the reason for the slow twist in such rifles, and you kind of touched on is that bench rest bullets have very thin jackets because they can make a thinner jacket more uniform, concentric, however you want to look at it, than a thicker one and that the slower twist is less damaging to that thin jacket. While on that note they also said that the bullets that blow up in fast calibers such as the 22-250 and 220 Swift do so solely to the bullet being destroyed in the barrel by longitudinal slits in the jacket by the rifling. Nothing else.

Lilja barrels are one of the best. I know you've done all that shooting as you have mentioned many times elsewhere.

Yep...
Saying that you can shoot bullets designed for fast twist in a barrel with fast twist is really not proving anything....

Decades of research and bullet making have basically shown that bullets have to be made for their intended twist rate and RPM or they strip or fail... Core strength and jacket thickness/strength seem to be the 2 biggest factors.... Most "Shooters" don't really know any of this or care... They just know that if they buy bullets made by Major manufacturers - they usually work if they aren't too long for the twist (Like trying to run 78g 223's in a 12-twist barrel)

The deal is.... If you are a Big Time bullet manufacturer (Sierra, Nosler, Hornady) making 223 bullets... and your bullets blow up, strip, or suffer core failures... you get the reputation for making junk... so you better darn well get it sorted out... BUT... 20 years ago - there were ALL sorts of failures like this... because most Commercial 223, 220 swift, and 22-250 rifles were set up with 1-12 twists... and bullets were made for 1-12 twists.... Then, folks shot the same 40 and 50g bullets in their AR's with 1-6 twists and 1-9 twist 220 swifts and 22-250's and had all sorts of issues with core stripping and blow ups.... so the bullet manufacturers had to make them more sturdy....

But.. Accuracy wise... Don't fool yourself... There's a huge difference between "Field" or "Hunting" accuracy and "Competition" accuracy... Most hunting - if you can hit a 1-gallon paint can at 100 yards most of the time - you will kill your quarry.... so a difference of 1/2 or 3/4 MOA isn't even noticed...

If faster twist really were an advantage to accuracy - I guarantee you that all the Benchrest and F-class guys would be shooting the fastest twists they can get.... But they are not.. They are shooting the slowest twists they can get away with... Even out at the 1,000 yard line....

Thanks

quote:

Decades of research and bullet making have basically shown that bullets have to be made for their intended twist rate and RPM or they strip or fail... Core strength and jacket thickness/strength seem to be the 2 biggest factors.... Most "Shooters" don't really know any of this or care... They just know that if they buy bullets made by Major manufacturers - they usually work if they aren't too long for the twist (Like trying to run 78g 223's in a 12-twist barrel)

You need to talk to all the bullet manufacturers. It's not the rpm that makes a bullet jacket fail. Take a light bullet for example in the 220 Swift. It's not the rpm that makes those bullets vaporize. Some more myths are the bullet cores melts or softens from friction heat and heat from the powder burn, plus air friction...then blows up from the rpm. Just not going to happen.

Also suggest talking to all the top benchrest barrel makers and ask them for "all" the reasons for slow twist and type of rifling while you're at it.

some will tell you it's to minimize jaxket damage.
the other half will say it's to keep the bullet barely enough stabilized.
so which one is correct?
if it's lead i'm going with jaxket deformation.
if it's jaxketed i'm going with... making it easier to move the bullet forward.
i call it the glide theory, move everything forward gently and then accelerate it.
seems to work with everything no matter the make-up.

Lamar,

That is exactly what you will hear from both the barrel makers and bullet makers. There just isn't enough time in the barrel to heat that core up. If that was even remotely true we'd have worse luck then we do with cast bullets. It's all in the jacket deformation. You will be told the bullet is destroyed in the barrel, not in the atmosphere. It depends on how tough the jacket is on how far out there you will see the grey mist if the velocity if high enough. One of the reasons for 5R rifling is so the rifling is easier on the bullet. Maybe that is a reason why Marlin went to micro groove rifling. There was another manufacturer that used micro groove in their 22's. I want to say Mossberg.

There's a lot more too it then twist and rpm.

quote:

Originally posted by SmokinJ:

You need to talk to all the bullet manufacturers. It's not the rpm that makes a bullet jacket fail. Take a light bullet for example in the 220 Swift. It's not the rpm that makes those bullets vaporize. Some more myths are the bullet cores melts or softens from friction heat and heat from the powder burn, plus air friction...then blows up from the rpm. Just not going to happen.

Also suggest talking to all the top benchrest barrel makers and ask them for "all" the reasons for slow twist and type of rifling while you're at it.

I have and your not making any sense... You are arguing contrary to stuff that was proven and sorted out long ago... 60+ years ago... That you are best off going with the slowest twist that will reliably stabilize the bullet you are shooting...

Do you not not believe that the US Military Marksmanship units shot TENS of MILLIONS of rounds testing out different twist rates for their High Power Competitions? What did they settle on for 308? Do you not believe that if they averaged 1 more X with a 1:10 twist - they would have scrapped every slower twist barrel they had?

But.. They scrapped all the 10 twist barrels for slower twists....

They did it for a reason....

I'm just saying the twist they chose wasn't chosen for the lower rpm alone. I was talking to Krieger this morning and though I'd ask about what we're talking about here. The reason that benchrest uses the slower twist is decided upon that all the bullets are not perfect (it's pretty likely that a perfect bullet doesn't exist)and the slower twist would less amplify an unbalance bullet. I asked if hypothetically we were to shoot all perfected balanced bullets would the faster twist matter then and the reply was no, it wouldn't affect the accuracy.

It boils down to basically the same argument of which is better, the 9mm or the 45acp. There are different camps that we fall into on barrel twists.

quote:

Originally posted by TruckJohn:

But.. They scrapped all the 10 twist barrels for slower twists....

They did it for a reason....

Gamers do things to win..... like pick a twist that barely stabilizes the bullet (of a certain length) at the required distance shot. BTW, that isn't a cast bullet either. Try shooting that setup 200 yards farther out or more and watch it fall on its face in the mud.

It seems that most of the detractors argue on the basis of jacketed bullets and BR or military practice and completely ignore that this discussion centers arround cast bullets. It is not necessarily aimed at using the fastest twist just to push boundaries but how HV can be obtained in the faster twist barrels usually available on some of the off the shelf or ex mil rifles casters often use. BR is a different proposition where a barrel will be chosen to optimise many factors that are not the premise of what may be intended as a field ready rifle. Often a jacketed bullet rifle sees double duty if it is not directly and exclusively dedicated to cast and therefore what it is is what has to be worked with and it is under these circumstances that the discussion is looking to maximise the velocity potential.

Casting actually amplifies the out of balance condition... Porosity and defects in casting are an ever present condition... There is literally no lead casting that is 100% free of all porosity and/or voids... All we can hope for is that on average - the porosity and voids are more or less uniformly distributed and won't hurt too much... but it's probably the most plausible explanation for the occasional "Flyers" we see when shooting cast...

(In my Day job - we have started moving from lead castings to cold forged lead components - as the lack of porosity in the cold forgings is a big advantage to the long term life of the finished product... I have sectioned and tested MANY lead castings and forgings as part of this...)

I also get that there is a big difference between fun shooting, hunting, and competition... where for fun shooting and especially hunting - Pinpoint accuracy isn't actually the #1 concern... Reliable performance is.... We do many things for "Hunting ammo" that wouldn't be acceptable for proper benchrest ammo.... but WE GOTTA be able to pull loaded rounds back out of the chamber... We can't have bullets too long for the magazine... We can't have bullets falling out or setting back massively in the magazine.. bullets HAVE to chamber every time without a fight.... AND.. They gotta shoot to a similar point of impact and can't go squirrely during vastly different environmental conditions....

But.. That wasn't the proposition that was made... The proposition made was that Twist rate has NO effect on accuracy at all... and that is false...

Thanks

quote:

Originally posted by TruckJohn:
Casting actually amplifies the out of balance condition... Porosity and defects in casting are an ever present condition... There is literally no lead casting that is 100% free of all porosity and/or voids... All we can hope for is that on average - the porosity and voids are more or less uniformly distributed and won't hurt too much... but it's probably the most plausible explanation for the occasional "Flyers" we see when shooting cast...

(In my Day job - we have started moving from lead castings to cold forged lead components - as the lack of porosity in the cold forgings is a big advantage to the long term life of the finished product... I have sectioned and tested MANY lead castings and forgings as part of this...)

I also get that there is a big difference between fun shooting, hunting, and competition... where for fun shooting and especially hunting - Pinpoint accuracy isn't actually the #1 concern... Reliable performance is.... We do many things for "Hunting ammo" that wouldn't be acceptable for proper benchrest ammo.... but WE GOTTA be able to pull loaded rounds back out of the chamber... We can't have bullets too long for the magazine... We can't have bullets falling out or setting back massively in the magazine.. bullets HAVE to chamber every time without a fight.... AND.. They gotta shoot to a similar point of impact and can't go squirrely during vastly different environmental conditions....

But.. That wasn't the proposition that was made... The proposition made was that Twist rate has NO effect on accuracy at all... and that is false...

Thanks

Well that's what Krieger said providing the bullets are perfect, which know they are not. We are doing very well with cast bullets at high velocity from fast to slow twist barrels, better then the average bear from the fast twist. There was a statement many years ago that there is a rpm threshold and if exceeded with fast twists inaccuracy would result. More then a handful of us have proven that wrong over and over and over.....and at long distance too because the argument went there too.

What alloy are you forging those bullets of? Are the bearing bands and lube groove forged in the same process?

quote:

Well that's what Krieger said providing the bullets are perfect, which know they are not. We are doing very well with cast bullets at high velocity from fast to slow twist barrels, better then the average bear from the fast twist. There was a statement many years ago that there is a rpm threshold and if exceeded with fast twists inaccuracy would result. More then a handful of us have proven that wrong over and over and over.....and at long distance too because the argument went there too.

There is a threshold.
Want to guess what it is?

that was funny sorta.
it was past my threshhold too.

quote:

Originally posted by SmokinJ:
I first met Don at the SHOT Show several years ago, where he Showed me some complicated computations proving why my empirically devised 4-to-1 powder-capacity formula actually works.

What's that then?
A 4-1 powder capacity formula.

I have a custom made bolt action 358 Winchester. It is based on a Remington action and fitted with a heavy 24" Douglas barrel. I originally requested a 1:10 twist but after talking with the smith settled for a 1:12 twist.
I shoot a 158 grain pistol bullet from that gun that only needs 1:18 twist to stabilize. At 2500 fps it shoots five shot groups into 0.3" groups from that 1:12 twist barrel. When someone talks to me about "over-stabilization" I just smile. How can anything be TOO stable?

I understand that if the bullet is too far out of balance the inertial forces can affect trajectory or even the integrity of the bullet. That is not from "over-stabilization" it is from flaws in the bullet that exceed the strength of its construction. If I drove those 158 grain pistol bullets fast enough I am sure I could get them to disintegrate in flight from the inertial forces of minor errors in the balance of the bullet.
I have seen benchrest shooters cuss the low temps at the range because their "perfect" system won't stabilize the bullets that they normally use in the colder temps. If they were using a tad more twist their rifle would be fine.

You cannot "over-stabilize" a bullet.

quote:

Originally posted by PaulS:
I have a custom made bolt action 358 Winchester. It is based on a Remington action and fitted with a heavy 24" Douglas barrel. I originally requested a 1:10 twist but after talking with the smith settled for a 1:12 twist.
I shoot a 158 grain pistol bullet from that gun that only needs 1:18 twist to stabilize. At 2500 fps it shoots five shot groups into 0.3" groups from that 1:12 twist barrel. When someone talks to me about "over-stabilization" I just smile. How can anything be TOO stable?

I understand that if the bullet is too far out of balance the inertial forces can affect trajectory or even the integrity of the bullet. That is not from "over-stabilization" it is from flaws in the bullet that exceed the strength of its construction. If I drove those 158 grain pistol bullets fast enough I am sure I could get them to disintegrate in flight from the inertial forces of minor errors in the balance of the bullet.
I have seen benchrest shooters cuss the low temps at the range because their "perfect" system won't stabilize the bullets that they normally use in the colder temps. If they were using a tad more twist their rifle would be fine.

You cannot "over-stabilize" a bullet.

Finally someone that really understands this. You make a lot of good points Paul.

quote:

3. The author shows a mixture of credible knowledge and questionable insight. For example, the statement, "Hydrogen molecules weigh less than carbon or oxygen molecules, so more H2O in the atmosphere reduces density." is ludicrous. Density has much less to do with what kind of molecules are present than it does with how closely packed those molecules are to each other. Steam is less dense than water and water is less dense than ice because of how close the water molecules are in each of those substances. If "more H2O in the atmosphere reduces density" then are we to believe that adding more and more H2O to the atmosphere will reduce density more and more? It is the H2O in fog that makes it more dense than dryer air, causing the fog to sink to ground level while the dryer, less dense air, floats above it. Again, the article is a mixture of fact and fiction.

It is false you know?
Ice is less dense than water thus it floats.

quote:

You cannot "over-stabilize" a bullet.

It is false you know?
Lets say you shoot a mile with a 45-70 to get a nice curved bullet path.
Ideally the front of the bullet will track the arch and hit the paper nose first and only leave a round hole.
If the bullet is over stabilised the nose will continue to point in the same direction it left the barrel and will make an oblong hole in the paper.
Not rocket science just physics.

So what is it?

The 4-1 powder capacity formula.

Smoking;
Thanks for posting your opening post.
Many years ago I built, the purests would correct me and say I assembled, a 25-06 using a Mark X action, factory barrel, Roberts or Richards stock.
I used the rifle mostly for ground hogs in Bath, Highland and Augusta counties, Virginia.
Any way I tried to use various 117-120 grain bullets with none being satisfactory. I thought that the heavier bullets would do better at longer ranges. I found that for all ranges that I shot, the Speer 100 grain hollow point was the bullet.
When I moved to Central Virginia I converted the Mark X to 375 Whelen using a Douglas barrel, for cast bullets exclusively. That's another story.
I bought a Remington Sendero in 25-06 with the idea of finding an accurate load using Sierra 120 grain HPBT. Not much luck there after a couple hundred test loads. So I got the bright idea that the barrel needed fire lapping. I got a smooth barrel and no better accuracy.
Seems this rifle also likes the 100 grain Speer bullets that I had left over from 25 years ago.
After reading your originating post I find that it's not bad juju nor is it I'm having a personality conflict with the heavy bullets.

Jim

quote:

Originally posted by The Dane:

quote:

You cannot "over-stabilize" a bullet.

It is false you know?
Lets say you shoot a mile with a 45-70 to get a nice curved bullet path.
Ideally the front of the bullet will track the arch and hit the paper nose first and only leave a round hole.
If the bullet is over stabilised the nose will continue to point in the same direction it left the barrel and will make an oblong hole in the paper.
Not rocket science just physics.

OK, I will concede to your point but at the same time I will ask will it affect the accuracy? I don't generally shoot beyond 600 yards as that is the limit of the local range and when hunting I shoot at maybe half that distance. It is unlikely that an "over-stabilized" bullet will have any adverse effects at those ranges.
All of the formula tell you what the approximate MINIMUM twist rate to stabilize the bullet is and not what the maximum twist is likely to be.

I think the problem we have here is that hunters and target shooters are trying to compare twist rates for their very different sports. I have used 130 grain bullets and 180 grain bullets to hunt with and if I had the gun set up at the minimum to stabilize the light bullet the heavy bullet would need a different gun in order to stabilize. Target shooters use a single bullet for the entire life of a barrel while hunters change components for different jobs. You must have at least the minimum twist rate for the longest bullet you will likely ever shoot.

quote:

Originally posted by The Dane:

quote:

You cannot "over-stabilize" a bullet.

It is false you know?
Lets say you shoot a mile with a 45-70 to get a nice curved bullet path.
Ideally the front of the bullet will track the arch and hit the paper nose first and only leave a round hole.
If the bullet is over stabilised the nose will continue to point in the same direction it left the barrel and will make an oblong hole in the paper.
Not rocket science just physics.

Except you forgot that by the time that bullet got to the mile mark the velocity has dropped considerably and the initial higher spin rate for it is much better if it had started from a slower twist barrel.

quote:

Originally posted by SmokinJ:

quote:

Originally posted by The Dane:

quote:

You cannot "over-stabilize" a bullet.

It is false you know?
Lets say you shoot a mile with a 45-70 to get a nice curved bullet path.
Ideally the front of the bullet will track the arch and hit the paper nose first and only leave a round hole.
If the bullet is over stabilised the nose will continue to point in the same direction it left the barrel and will make an oblong hole in the paper.
Not rocket science just physics.

Except you forgot that by the time that bullet got to the mile mark the velocity has dropped considerably and the initial higher spin rate for it is much better if it had started from a slower twist barrel.

Except you forgot that when the bullet is not traveling point on the ballistic coefficient is degraded. The nose up bullet will also drift more. You cannot escape the laws of physics.
Which shows your premis is BS. You don't know enough physics to either defend or attack.

Hey Fellas;
When you take time from your arguing and insults, maybe you could answer a question. What rifling twist would be best for accurate shooting of 117 - 120 grain bullets in the 25-06.
For me, the 1 in 10 just didn't work in two rifles.


Jim

quote:

Originally posted by arkypete:
Hey Fellas;
When you take time from your arguing and insults, maybe you could answer a question. What rifling twist would be best for accurate shooting of 117 - 120 grain bullets in the 25-06.
For me, the 1 in 10 just didn't work in two rifles.


Jim

Jim we very well know who the trouble maker is and I'm not arguing with him. I'm in fact glad to see you moved this thread along.

With that said the 1 in 10 twist is the most common twist for the 25 caliber barrels. There are some exceptions and I'll name one and that is the 257 Weatherby Magnum. It's 1 in 12.

You bullets weights you are shooting are the upper weights for that caliber. That would suggest them needing the faster twist. I don't know what you have tried,like different brand bullets, different types of powder, different bullet seating depths, etc., and this doesn't even cover the rifle itself. If the bullet holes on the target had the "coma" or aren't exactly round, possibly even some showing the bullet is starting to keyhole what makes you think it's the twist?

Smoking;

Most if not all of the heavy weight bullets for the 25-06 have been hollow point boat tails.
The most accurate bullet has been the Speer 100 grain flat base hollow point.
I've popped a number of groundhogs with this bullet 300 and 400 yards. I won't bore with my ratio of hits to misses, I was content.
Now would the issue be resolved if I were to find flat based bullets in the 117 - 120 grain range?
The Scotch side of my ancestery would be totally outraged at scrpping an Remington barrel that's only had 3 or 400 shots.
Thanks again for bringing up the topic.

Jim

Well you know they say the twist is calculated for the length of the bullet, but as we know the weight goes up with length. So I the worse for your barrel would be the boat tail heavy weights as they would be the longest. You now I had a friend who owned a Ruger Varminter in 22-250 with a 14 twist. It shot really well. He bought a box of those Sierra 63 grain semi points which were suppose to shoot in that fast of a twist and they did from many of them, but not his. His rifle flat out keyholed them. Maybe you just have a barrel that was like his and not like the heavier bullets.

By the way that's some darn good long range hog shooting for sure. That's a lot of fun. Do you think you can be happy with that 100 grain? Why do you want to go heavier?

Smokin

Like most reloading tinkerers once I find something that works, there's bound to be something better that I've not tried.
The hundred grainer is accurate and exposively effective, I'm wondering if a heavier bullet would be better at 500 plus yards.
I think I'll get some of the 115-117 spitzer bullets and see what they do and report back.

Jim

Jim,

Nothing at all wrong with tinkering, that's how you learn things about your load and rifle.

So have you shot any of the heavier bullet yet, I'm confused? I thought from you post that you did and the accuracy wasn't so good.

quote:

Originally posted by SmokinJ:
Jim,

Nothing at all wrong with tinkering, that's how you learn things about your load and rifle.

So have you shot any of the heavier bullet yet, I'm confused? I thought from you post that you did and the accuracy wasn't so good.

Smoking;
Yes, I've tried the 117 - 120 grain bullets as far back as 30 years ago with a MarkX Mauser with so-so results, then I tried the same bullets in my Remington Sendero with similar results, mostly half donkey.
There's not many flat based, spitzers in the 117-120 in 25 caliber that are resonably priced.
I may investigate making my own cup and core 25 caliber bullets, I've got the Corbin press and have made my own Base Gard bullets for my pistols.

Thanks

jim

Jim,

I've never gotten into swaging jacketed bullets and wish would have now. I have swaged cast bullets and still do.

I'll tell you if you can get some real precise jackets you have it made with your swage. Just a thought but wonder if you can swage those heavier boat tailed factory jacketed bullets into flat bases without ruining them?