.223 Best All Around Twist Rate

[captonion]

I did explain it, it obviously didn't sink in!
Maybe do a bit of research before you completely discount without knowing for sure..

Barrel life: Heat is the biggest factor.. Tighter twist barrels create more friction that results in heat..
Shooting the same load out of two of my rifles (same make barrel/ length). Only difference being rate of twist, one is 1/10 the other 1/8..Shot through the same Chrony at same distance there is about a 90fps difference.. A result of more friction which creates more heat, and I suspect higher pressure.. Got a Laser heat gun to find out actual heat difference this spring..

"Over-stabilization tends to cause the tip of the bullet to point skyward rather than downward after the apex of the trajectory arch, this has negative effect on predictable wind drift.."

Accuracy up to the point of the apex of the arch if fine, its after that this effect causes exaggerated wind drift...Taught this by a friend who has been shooting long distance competitions around the world longer than I have been shooting... This is the reason competition shooters choose the slowest twist rate possible that will stabilize the length of bullet they choose to shoot, because the results are far better accuracy

 

[Boomer]

The friction on the bullet would be almost the same whether the lands were straight producing no spin or whether the twist was 1:7. The average velocity of slow twist and fast twist barrels with the same loads supports this.

From page 143 of Bryan Lit's "Applied Ballistics for Long Range Shooting" . . .
"The most important lesson to take away from this stability analysis is that the bullet does not experience significantly more drag if its flying with excessive stability. The fear of increased drag due to over-stabilization is unfounded. . . . "

What this means is that the bullet is not in a nose up attitude in flight, if it were BC would suffer because the side, rather than the point of the bullet would be the leading edge. If there is no nose up attitude in flight, there can be no negative effect on wind drift.

 

[CV32]

From AccurateShooter.com:

On the Applied Ballistics Facebook page, Ballistician Bryan Litz regularly offers a “Tuesday Trivia” question about ballistics.

Today’s brain-teaser is a true/false question about bullet stabilization. On shooting forums you often find heated arguments about “over-stabilization”. Bryan wants readers to consider the issue of over-stabilization and answer a challenge question…

Is This Statement TRUE or FALSE?

“The problem with ‘over-stabilizing’ a bullet (by shooting it from an excessively fast twist rate) is that the bullet will fly ‘nose high’ on a long range shot. The nose-high orientation induces extra drag and reduces the effective BC of the bullet.”

True or False, and WHY?

...

For practical purposes, the answer is FALSE

As a bullet arcs on a long range trajectory, it’s axis is torqued (by aerodynamic forces) to constantly align with the oncoming airflow. When a spinning object has its axis torqued, the object reacts by pointing its axis primarily ‘out of plane’; 90 degrees from the applied force. This results in a nose-right orientation (for right twist barrels) known as the yaw of repose. The yaw of repose steers the bullet ever so slightly to the side resulting in gyroscopic (spin) drift.

The bullet nose will point slightly above its velocity vector (pitch), but that pitch is only about 1/10 of the yaw of repose which is not enough to cause a practical vertical drift (less than 1/2″ at 1000 yards). Typical yaw of repose remains below 1/60th of one degree, while pitch is on the order of 1/600th of one degree. This small amount of pitch and yaw is not enough to induce a measurable amount of additional drag, even for highly stabilized bullets.

All of the above applies to stable projectiles in supersonic flight on ‘flat fire’ trajectories. For projectiles fired at high angles (above ~10-20 degrees above the line of sight), it is possible for the bullet to not track, or trace with the trajectory. This is a common design challenge for artillery shells that are often fired on high angle trajectories. The axis of the spinning shell may be too rigid to bend with the exaggerated trajectory. In that case the shell can ‘belly flop’, or fall base first. However for small arms projectiles on flat-fire trajectories, this isn’t a problem.

Another consideration with spinning a bullet too fast is related to bullet failure. This discussion assumes the bullet remains structurally in tact.

Dynamic instability during transonic flight is also a different problem, not related to the above discussion.

 

[captonion]

The friction on the bullet would be almost the same whether the lands were straight producing no spin or whether the twist was 1:7. The average velocity of slow twist and fast twist barrels with the same loads supports this..

90fps difference in my own tests prove otherwise from a 1/10 to a 1/8 difference, I have also recorded a 40fps difference in a 1/10 to 1/9 difference in .243 with the same length barrel/same load.. Peaked my interest, so I asked around, and did a bit of homework to find it to be true.. I am interested to the point of buying a laser heat gun to find out the heat difference this spring..

From AccurateShooter.com:

As for the nose high deal, I get this from a highly decorated life long competition shooter who has competed world wide. I have no reason not to believe him.... I am sure you could google up theories for and against both, so no matter of what you may have googled up I will go with his word...

 

[CV32]

As for the nose high deal, I get this from a highly decorated life long competition shooter who has competed world wide. I have no reason not to believe him.... I am sure you could google up theories for and against both, so no matter of what you may have googled up I will go with his word...

Bryan Litz is a well known ballistics expert (for Berger Bullets and otherwise) with a pretty impressive resume and a staff of engineers at his own company Applied Ballistics.

Bryan earned his Aerospace Engineering degree from Pennsylvania State University in 2002. For the next 6 years, he worked for the US Air Force on Air-to-air missile design, modeling and simulation. In November 2008, he left the government and became the Chief Ballistician for Berger Bullets. Bryan founded Applied Ballistics and has produced numerous articles, books, and videos related to the science of long range shooting.

While I am sure you have every good reason to implicitly trust your friend's opinion, it might well be that his opinion is an entrenchment of commonly held views and myths that aren't actually based in science. Something hinted at by Litz's 'true or false' discussion earlier.

 

[captonion]

While I am sure you have every good reason to implicitly trust your friend's opinion, it might well be that his opinion is an entrenchment of commonly held views and myths that aren't actually based in science. Something hinted at by Litz's 'true or false' discussion earlier.

Just talked to him,I will quote it the best I can..
The longer the bullet, the more chance there is the bullet has imperfections. These imperfections are amplified by rate of twist which he calls unbalanced aerodynamics...This is what he says causes the nose up..The reason that the majority of competition long range shooters choose the slowest rate of twist that can stabilize the desired bullet.

He went further telling me it is a bit more complicated than that to explain bullet flight and he will explain more (show me) next time I am home from alberta...

 

[CV32]

Just talked to him,I will quote it the best I can.. The longer the bullet, the more chance there is the bullet has imperfections. These imperfections are amplified by rate of twist which he calls unbalanced aerodynamics...This is what he says causes the nose up..The reason that the majority of competition long range shooters choose the slowest rate of twist that can stabilize the desired bullet. He went further telling me it is a bit more complicated than that to explain bullet flight and he will explain more (show me) next time I am home from alberta...

It is certainly true that a faster twist barrel is less forgiving of imperfections in a bullet. It is better explained here: Barrel Twist & Bullet Stability. And if you're a real grognard, in books like Modern Exterior Ballistics: The Launch and Flight Dynamics of Symmetric Projectiles (Robert McCoy) and Modern Advancements in Long Range Shooting: Volume I (Bryan Litz).

But bullet imperfections are always going to have negative effects, and its a poor reason to substitute longer, heavier bullets (with better BC, etc) in a fast twist with shorter, lighter bullets (with less impressive BC, etc) for long range shooting. Otherwise, we wouldn't bother with longer (and heavier) rounds like .338 Lapua and .50 BMG because of the increased possibility of imperfections. For LR shooting, most folks are probably going to pick 175 gr bullets in a 1 in 10 twist .308 over 168 gr bullets in a 1 in 12 twist .308, simply because the longer (and heavier) bullets tend to perform better at those extended distances. And they're probably going to be buying their projectiles from a source that produces very consistent bullets.

 

[sobo4303]

I prefer a 1-12" and keep the bullet weight to 50-55gr .Tightening the twist and loading heavier bullets didn't make it a better killer IMO ........less wind drift and better penetration aside it is what it is........ better on varmints. The Soviets AK 74 round also went out the backdoor as vets preferred the 7.62x39 rd given the choice.The AK74 round had an air pocket in the nose while still FMJ to make the bullet Geneva approved, tumbled on contact causing horrific exit wounds.First used in Afghanistan in the 80's...........Harold

Best reply yet. I shoot 40 and 50 grainers out of my Rem Varmint. I have shot many other 223 rifles (Savage, Tikka, Weatherby) with the same ammo (worked up loads obviously for each rifle) with the barrel twists being 1-8 and 1-9. None of the groupings were as tight as my Remmy. My experience has been 1-12 twists and a good bipod = gopher headshot at 300 yards all day long.

 

[captonion]

Thank you for your response CV32. Much of your found info explains why the slowest possible twist rate to suit the bullet being used for optimal accuracy... Thanks again.

 

[captonion]

There is no such thing as over stabilization.

You are correct, It is that the bullet is spun too fast to have the best possible stabilization. I guess over stabilization is easier to say..

This is a deep subject of which interests me.. I am thankful I have someone to teach me with first hand information, just wish I could take in the info as quick as it is put forward..

 

[Boomer]

90fps difference in my own tests prove otherwise from a 1/10 to a 1/8 difference, I have also recorded a 40fps difference in a 1/10 to 1/9 difference in .243 with the same length barrel/same load.. Peaked my interest, so I asked around, and did a bit of homework to find it to be true.. I am interested to the point of buying a laser heat gun to find out the heat difference this spring..
. . .

Those velocity differences might well occur when shooting the same load in two different barrels having the same twist, just as you will not get identical velocities to those which appear in the loading manuals, opposite the specific load data. Barrels are individuals, that produce individual results. A better test is to take an average velocity at the muzzle and an average velocity down range, say 300 yards. If there were say a larger difference in the muzzle velocity and the down range velocity with a fast twist barrel, then there was with a slow twist barrel, you would be correct, but that has not been my observation.

Bryal Litz has two editions of his first book out now, plus an additional 3, all of which are valuable references, and will be less expensive than the laser thermometer that only provides you with a single piece of information; maybe you could rent one for the day of your experiment. In any case, its erosion caused by hot, high pressure gases that erode the throat of the chamber that degrades the accuracy of the barrel. You don't need a fancy thermometer to prove this, after firing a short string, put you hand on the barrel and you can tell pretty quickly which part is the hottest.

The techno geek engineers today have a much better understanding of internal ballistics than the shooters and bullet designers of 30 years ago. Many of the questions that were left unanswered in the understanding of what happens subsequent to a bit of pressure on a trigger, is now understood. As a result we have better bullets, better propellants, and better barrels.

 

[bogie]

Just in time for me to work up a new series of loads for my CZ527 223. Its a gorgeous rifle and I didnt want to sell it to get a "better" twist rate. I have a better idea now why CZ still does a 1:12 twist. Needless to say rebarreling would be quite expensive. I have an assortment of 50-60gr bullets and some new powders to load up. FWIW I usually start with the "most accurate" loads in my Nozler reloading manual. It was right on the money with my 308 and 30-06 loads. The accuracy loads they are talking about come up with H335 and Benchrest powders too so it all seems to agree. Got a Nikon Buckmaster 6-16 on it so optics are covered. Thanks so much for the edjamacation guys. This has been good reading. Too much info is so much better than not enough. Now if I could find some time to do some loads.....

 

[CV32]

Just in time for me to work up a new series of loads for my CZ527 223.

Great rifle.

 

[bogie]

Thanks CV32. One benefit I was not aware of till I got it was it is exactly the same weight as my CZ452. 5.2lbs or so. I really didnt want to sell it to get something else. Shes a keeper. Replaced a Ruger No 1 that was in the 50 percentile that didnt shoot so well. Looking forward to stuffing some cases with all this new info. Love this site. Got a large pile of Winchester headstamp cases all prepped and ready to roll.

 

[Boomer]

Great rifle.

I'll second that. I have one of the full stock versions in .223, and I'm having a lot of fun with it. By the way, if you're interested, I wasn't overwhelmed with the factory sights on mine, so I got a NECG ghost ring and a Patridge brass faced front sight for it. With the Warne QD rings, I can switch between irons and optics at will, and both seem to provide repeatable zeros provides I pay attention to the position of the levers on the rings and the slot of the screw on the ghost ring.

NECG ghost ring

Don't be put off by the uneven contact with the receiver, its my fault, when bottomed out the stem of the ghost ring extends below the sight base

I found that the window in the sight hood puts a distracting shadow across the face of the sight . . .

So I remove it when shooting . . .

For those wondering, this is why its called a ghost ring

Usually I don't like "big scopes" on small rifles, but . . .

The medium height rings provide just enough clearance for a 40mm objective

 

[bogie]

I have an American and it did not come with sights. The Nikon scope I have on it has an enormous eye relief and amazing glass. My 65yr old eyes can see forever in it. Nikons are probably the best bang for buck in scopes currently. I have VXIII Leupys on my 30cals but only because I had them. Got Nikon Prostaffs on my CZ452 and its amazingly clear. Usually the Nikons have at least another inch of eye relief so setup is much easier.

 

[captonion]

The friction on the bullet would be almost the same whether the lands were straight producing no spin or whether the twist was 1:7. The average velocity of slow twist and fast twist barrels with the same loads supports this.

Those velocity differences might well occur when shooting the same load in two different barrels having the same twist, just as you will not get identical velocities to those which appear in the loading manuals, opposite the specific load data. Barrels are individuals, that produce individual results

.

Soooo which is it? Difference or no difference?
What I get from this is, there can be a 90fps difference from two barrels with the same rate of twist and length, but no difference when a change in rate of twist comes into play?

A better test is to take an average velocity at the muzzle and an average velocity down range, say 300 yards. If there were say a larger difference in the muzzle velocity and the down range velocity with a fast twist barrel, then there was with a slow twist barrel, you would be correct, but that has not been my observation.

My test, though small was certainly adequate to see for myself what I have been hearing/reading about to hold water.. Seeing if there was a reduction in muzzle velocity is what I was after and there was that. 90fps in .223, and 40+fps in .243(just 1" gain).. No need to go out to 300yds, muzzle velocity was what the test was all about..

It is common sense that a tighter twist barrel will have more resistance to push the bullet through the bore creating more friction and a reduction in velocity.. What is it that causes jacket failure in these tight twist barrels? Is it the stress that the bullet/jacket is subjected to by being forced down the tighter twist barrel that play a part? Common sense would say so!
More resistance = friction = more pressure/heat.. How much heat? Tests to be done this spring..

You don't need a fancy thermometer to prove this, after firing a short string, put you hand on the barrel and you can tell pretty quickly which part is the hottest..

Hand test? Really?

Seems to me, you just want an argument... You even argue against your very own statements..

 

[Boomer]

.

Soooo which is it? Difference or no difference?
What I get from this is, there can be a 90fps difference from two barrels with the same rate of twist and length, but no difference when a change in rate of twist comes into play?

My point is that since you can't change the rate of twist in a single barrel, any observed difference in velocity between two barrels can be attributed to factors other than rate of twist. To test in any sort of meaningful way, the bullet velocity from each barrel has to be measured both at the muzzle and down range. If the bullet tips enough to affect it's BC, the difference between the recorded muzzle velocity and the recorded down range velocity will indicate if there is a loss of BC. If there is a greater difference in average velocity for the fast twist barrel, its because BC is degraded. Quite possibly though the faster twist barrel shows a higher down range velocity because upon exiting the muzzle, it's bullet suffers from precession for a shorter period of time. A bullet in yaw is not very slippery.

My test, though small was certainly adequate to see for myself what I have been hearing/reading about to hold water.. Seeing if there was a reduction in muzzle velocity is what I was after and there was that. 90fps in .223, and 40+fps in .243(just 1" gain).. No need to go out to 300yds, muzzle velocity was what the test was all about..

Again, you're comparing two different barrels that have more differences than simply rate of twist. The length and smoothness of the lead is different, the actual diameter of the bore and it's smoothness is different, and additionally, I doubt if you've determined the degree of error in your chronograph readings. To find out what is really going on, not only do you have to measure the velocity at both the muzzle and at 300 yards, but both velocities at both ranges must be measured for each shot which requires two chronographs, and both chronographs must be synchronized.

It is common sense that a tighter twist barrel will have more resistance to push the bullet through the bore creating more friction and a reduction in velocity.. What is it that causes jacket failure in these tight twist barrels? Is it the stress that the bullet/jacket is subjected to by being forced down the tighter twist barrel that play a part? Common sense would say so!
More resistance = friction = more pressure/heat.. How much heat? Tests to be done this spring..

Twist has little effect on friction. Ackley showed that it takes approximately 30% of the propellant energy to spin the bullet, the amount of spin does not change this. I have a 28" 1:8 .308 with a long throat which produces 2650 fps with 210 gr VLDs. According to your philosophy, that would not be possible. When light jacketed bullets fail in flight, its due to the high centrifugal force which overcomes the structural integrity of the jacket, it only occurs with bullets that are intended to violently upset at .22 Hornet - .222 Remington velocities

Hand test? Really?

Seems to me, you just want an argument... You even argue against your very own statements..

When I see someone is misinformed I try to help out; whether or not I'm successful is determined by that individual, sort of a leading a horse to water sort of thing. The hottest part of the barrel is directly over the lead, and heat dissipates as you move down the barrel towards the muzzle. This isn't rocket science. The amount of heat felt is determined by the contour of the barrel, and the amount of powder in the charge, and since any degree of twist takes approximately 30% of the chemical energy of the propellant, the heat felt is irregardless of the degree of twist which still lies ahead of the bullet. Lets assume you make up two loads, both loads have the same powder charge and same bullets, but one bullet has a jump to the lands while the other is jammed. The jammed bullet produced much higher pressure before the bullet can move, so it might be interesting to do that test first, and see what the difference in heat is for each barrel, before worrying about how much additional heat created by a faster twist.

 

[hoytcanon]

Again, you're comparing two different barrels that have more differences than simply rate of twist. The length and smoothness of the lead is different, the actual diameter of the bore and it's smoothness is different...

This is the key... Captonian, you have far too many variables and far too small a sample size to draw "any" conclusions from your testing... statistical analysis is a complex process when variables are limited... in the testing you are doing there are far too many to control and thus no legitimate conclusion can be drawn. In addition, testing for heat in two different barrels, in an attempt to draw the conclusion you are determined to prove, is pointless.

 

[captonion]

You should be a politician!

First you say there would be NO difference (your findings). Then you list ways why the difference... Come on now, you are back peddling pretty hard here..