over stabilized bullets

[scott2506]

I've been shooting and hunting for years, and learn something new all the time. While shooting my Ruger M77 MkII 25-06, using Sierra 90 blitzking at 3570 fps from my 26 inch bbl.. I found out that my drop chart was wayyyyy off. I know paper charts and real life are not the same, but most of the time It has got me close.
I am running low on my 115 Berger bullets and know varmint bullet kill coyotes so much better (dump all of energy into them) I thought I would test the 90's out at 400 and 600 yards.. with a 200 yard zero. my 2.25 inch group at 425 yards was 3 inches right. and about 2 inches lower than the chart.
at 625 yards my group was 9 inches right and a ft lower than what my drop chart said. and also a foot to the right.

I used to regularly shoot water jugs at 500 yards 1st shot using my drop charts.. my errors on paper was either rifle cant (no level) or my shooting error.

although my 115 Bergers shoot well. and hold 1/2 most the time out to long range, I would like to make a true varmint bullet work out to this range.

After some research I found out that bullet that are spun too fast, will not go to sleep and cause problems.

Years ago I used to load my 85 Ballistic tips to 3700 fps... at 300 yards I was getting 4-5 inch groups, but when I backed them down to 3400 fps, they was well under moa.. jackets coming apart? Nope, I've seen this happen when I shoot 110 Vmaxes out of my 300 Winny at 3700 fps, one out of 10 makes it to target at 100 yards. When a jacket comes apart, then they never make it to target.

I came across a few links and it is common if bullets are spun too fast then at long range where a rifle axis of deg is pointed up, the bullet will not nose down like most bullets do.. I think it's called "spherical precession"

What the bullet is doing is NOT nosing down in flight (long range.. the upward pointed bullet is now skidding on the air.. a right twist would make the bullet like a paddle wheel on the air (from rifling marks) spinning at 200,000+ rpm's veering to the right and killing the drag coefficient

Some say that you can not over stabilize a bullets. ??
if you never shoot past 400 yards, then you'll probably never know what this is about. most never shot past 100 yards.


This is opinion vs real life.

REAL life=
Bryan Litz explains this all too well. He is the head engineer of Berger bullets. an champion national shooter, worked for the military on the subject, and an expert in ballistics. Berger Bullets are probably the the most accurate bullets on the face of the Earth for long range shooting.

I said above I learn something new everyday, and yes this can happen. my 2506 is a 10 twist, best for 100-120 grain bullets at around 2900-3200 fps
so a 90 at 3570 (I loaded them down from 3650 fps) fps is too many rpms for the shorter bullets to go sleep.

Bullet stabilizing can sometimes be a balance.
too little spin and bullets tumble (I've experienced this too).. too much spin and bullet never goes to sleep. nose of bullet at long range will still be pointed up while bullet is traveling downward.. and bullet drag BC will suffer greatly.

most people will never experience this because they either have never shot past 500 yards or shot past 500 yards with varmint bullets in a 10 twist.

I can say I Learn something new all the time.

PS I loaded them down to 3400 fps and will test them soon and let you know.

 

[6724]

this ought to be good, let me get my popcorn and a beer!

bullets going to "sleep" hmmm?


didnt i see some test a while back that showed that while bergers are good, sierra and speer and just about every other bullet manufacturer makes very accurate bullets.

theory about nosing over, i want to hear the physics behind whether or not a bullet noses over, and why.

 

[OldTurtle]

Quote:this ought to be good, let me get my popcorn and a beer!..bullets going to "sleep" hmmm?.....It's been my understanding that bullets, when slowing to the "below speed of sound' point, do tend to have a change in performance that is referred to as "Going to Sleep"...Before you get too stuffed on popcorn and beer, you might want to check into it...

 

[Pete Robinette]

I appreciate the information it is pretty interesting. It's one mans opinion and we can believe it or not. I don't by any means think that the post was telling us that this is the truth and no other opinion matters. What I do know is I can't stand smart remarks when someone offers there knowledge or opionion. Hmmmmm?
I'm not some liberal we all must get a trophy person but if you can't offer a different theory or describe why you think different without sarcasm then why post?

 

[6724]

i find the original post condescending.

perhaps if you are going to proclaim that others are too ignorant to know what you are talking about, perhaps you can enlighten the rest of us with some actual physics?

 

[venatic]

I have locked down the original post on this subject less than two hours ago and I find it very suspicious that the same argument pops up again but with different players.
I will watch this conversation closely so ya’ll disagree politely and all is good.

 

[Pete Robinette]

Well, you just proved my point. There was no mention of ignorance in the post. If you feel I was calling you ignorant then you are reading what you want to read.
I don't know if the guy knows one hill of beans about what he is talking about but I do think that it is a theory. If I want to learn more then I will dig into it. I may find proof of the theory or might find information I believe proves it wrong in my mind.
I neither stated I new anything about physics. I stated if "YOU" weren't offering another theory on "physics" then why post a sarcastic post? Why not add to the post in a positive way?

 

[Furhunter]

This isn't going anywhere good.

 

[Vapor]

Originally Posted By: OldTurtle.....It's been my understanding that bullets, when slowing to the "below speed of sound' point, do tend to have a change in performance that is referred to as "Going to Sleep"...Before you get too stuffed on popcorn and beer, you might want to check into it...

That's not what "goes to sleep" actually refers to though. What you're thinking of is actually the opposite.

As Litz points out, a bullet starts out leaving the barrel with a pitch/yaw that slowly settles out as the bullet gains gyroscopic stability over a set amount of time/distance.
The pitch/yaw is caused by run out in the cartridge, inconsistent drag in the barrel rifling or even a sudden rush of gas exiting the muzzle in a non-concentric fassion.

Much the same way an arrow in flight gains stability after it leaves the bow. The difference being that an arrow becomes stable because of drag inflicted by the fletchings...a bullet does it because of the aerodynamics of the tip, and the drag at the rear.

Now, weather or not a bullet can be spun to fast is not the question. They can.
The issue you seem to be concerned with, is if spinning a bullet TOO FAST will effect it's trajectory due to increasing it's drag.

While reducing the RMPs will most certainly effect stability...I would have a hard time believing that increasing a bullets RPMs would effect the stability negatively.
I can agree that increasing the RPMs will reduce the drag as the speed of the air moving across the bullet will increase...but I don't believe that it would be at a level that will effect POI, at least not at the level you're talking about.

You would see drastic pressure spikes due to increasing the twist of your barrel to bullet ratio, before you would see any ill effect from reducing it's ability to "go to sleep"

It's already been well documented that just because it has been proven that bullets can in fact, "go to sleep"...it doesn't have the accuracy impact that was once suggested.

At one time, it was stated that a bullet could be fired into a better group at 3-500 yds...than it could produce at 100 yds.
That's just silly.
99% of the time, it's any of a number of other issues...most commonly parallax...but that's a discussion for another day.

 

[3DHUSKER]

Originally Posted By: Vapor

That's not what "goes to sleep" actually refers to though. What you're thinking of is actually the opposite.

As Litz points out, a bullet starts out leaving the barrel with a pitch/yaw that slowly settles out as the bullet gains gyroscopic stability over a set amount of time/distance.
The pitch/yaw is caused by run out in the cartridge, inconsistent drag in the barrel rifling or even a sudden rush of gas exiting the muzzle in a non-concentric fassion.

Much the same way an arrow in flight gains stability after it leaves the bow. The difference being that an arrow becomes stable because of drag inflicted by the fletchings...a bullet does it because of the aerodynamics of the tip, and the drag at the rear.

Now, weather or not a bullet can be spun to fast is not the question. They can.
The issue you seem to be concerned with, is if spinning a bullet TOO FAST will effect it's trajectory due to increasing it's drag.

While reducing the RMPs will most certainly effect stability...I would have a hard time believing that increasing a bullets RPMs would effect the stability negatively.
I can agree that increasing the RPMs will reduce the drag as the speed of the air moving across the bullet will increase...but I don't believe that it would be at a level that will effect POI, at least not at the level you're talking about.

You would see drastic pressure spikes due to increasing the twist of your barrel to bullet ratio, before you would see any ill effect from reducing it's ability to "go to sleep"

It's already been well documented that just because it has been proven that bullets can in fact, "go to sleep"...it doesn't have the accuracy impact that was once suggested.

At one time, it was stated that a bullet could be fired into a better group at 3-500 yds...than it could produce at 100 yds.
That's just silly.
99% of the time, it's any of a number of other issues...most commonly parallax...but that's a discussion for another day.

Best post I have seen in a long while.

 

[orkan]

Originally Posted By: VaporAt one time, it was stated that a bullet could be fired into a better group at 3-500 yds...than it could produce at 100 yds.
That's just silly. A better group measured linearly? Not so much. A better group measured angularly? Absolutely. I see it pretty frequently with .375CT. Just today I was shooting a rifle that produced no better than a 1 MOA group at 100yds. That same rifle turned in a 6" 5-shot group at 975yds. Four of those rounds could be covered by a business card.

I have researched this subject at length. Had conversations with Bryan Litz, Kirby Allen, and a few other recognizable names. I feel I have a good grasp on why it happens, however, it's been my experience that the talk of the specific physics involved, seems to bring out the worst in every internet forum. I'll leave that discussion to those that want to debate it. Whether debating its existence, or why it exists... threads always seem to turn out the same way every in which every thread with entrenched viewpoints turns out. Sad, but true in my experience. Yet the simple fact remains that regardless of how God sees us, or how we see each other, we are not all equal. Some have the ability to grasp higher mathematical concepts. I'm nowhere near the mathematical ability of someone like Bryan Litz, however, I have a pretty good understanding of physics. So for those of you wanting to learn about it, the information is out there. Don't be intimidated, and be persistent. This isn't a concept you'll be able to put to bed in a single day's research. Learning about this principle of aerodynamics as it pertains to spin-stabilized projectiles will likely lead you down a few other paths as well, and can greatly affect your understanding of the sport of shooting.

I will simply say that a few years ago when I began working with .375CT, I ran into the problem of 1-moa groups at 100yds, turning into half or quarter moa groups at distance. I was perplexed, and sought as much information as I could attain in order to be able to fully understand and explain the phenomenon. It took a while.

Though when talking with customers whom are buying .375CT rifles from us, I try not to get into the physics too much. I simply tell them: "Don't expect sub-MOA at 100yds. Expect it at 500-1500yds." If they ask why, I direct them to Litz's book as a starting point.

The truth is out there. (I loved the xfiles... I admit it)

 

[scott2506]

what org post, I am explaining my problem and no two people have the same fix or opinions.

 

[scott2506]

True- There is a lot we don't understand. I too have witnessed better MOA groups from 200-400 than 100 yards, physics say this is not possible. even old timers who bench rest told me this years ago, Did not believe till I seen it.

most will never try and shoot varmint bullet out to 600 yards. and then most would have a slow twist rifle in 22-250 etc.. 10 twists shooting this skin varmint bullets at 600 yards. Your mileage may vary. mine was not good.

 

[CatShooter]

I'm not going to play in this, other than to point out some glaring problems with what has been said so far.

Brian Litz claimed that bullets can leave the barrel of a light weight gun barrel at 10° off axis, and then find their way back to shoot straight, and from a heavy barrel, they leave straight - so from a light weight barrel, the bullet has a much lower BC - id est, bullet BC is dependent on barrel weight?? Brian Litz has made many erronious statements in public and in his articles and book...

Those that believe that bullets "are awake" and then go to sleep, have to believe that a bullet can leave the muzzle and go off in a different direction, and then, some how, realize the error of it's ways, change direction and go back to the original path, and then change direction again to stay on that path. That is THREE direction changes, without any cause, and all the while, the world is spinning in front of it at 250,0000 rpm... exactly HOW does a stupid bullet find it's way back to the true course, and then change direction again to stay on the true course. How does it do this magic thing?

Comparing a bullet's stability to an arrow, should be obvious - an arrow has a heavy nose and tail feathers - so the nose leads. Most bullets have a heavy tail, and no feathers, so how does a bullet fly like an arrow?... or even, how does a bullet fly at all.


People say that bulets can't be accurate at or below the speed of sound - why?? The bullets do NOT pass through any "turbulence". And how do people shoot accurately at 2000 yards and further?

These are just a few of the very flawed statements presented here - and it goes on...

 

[ninehorses]

CatShooter,

Please explain how a bullet will settle down in flight to produce better groups at 300, than at 100 yards, if this is possible(as posted above). Or, would these good groups at 300, been good if shot at 100. We all have shot a GREAT group at a hundred, but can't seem to repeat it with the same load. One would think that if a bullet was wobbling at the muzzle, the farther it goes the worse the wobble would get, it is slowing down.

I am also wondering how the OP was pushing a 85 grain Nosler at 3700 out of his 25-06. I get good accuracy with the 85's with RE 19, 56.5 grains, runs around 3550 fps. In four rifles this is a good load, and is close to max buy the way the primers look.

The OP states his drop charts are wrong, it could be that he's not shooting as fast as he thinks. Just an observation.

I have Bryan's book, but I'm not ashamed to say reading it gives me a headache. Just too tech. in a lot of ways. SO... Keep it simple.

 

[CatShooter]

Originally Posted By: ninehorsesCatShooter,

Please explain how a bullet will settle down in flight to produce better groups at 300, than at 100 yards, if this is possible. Or, would these good groups at 300, been good if shot at 100. We all have shot a GREAT group at a hundred, but can't seem to repeat it with the same load.

I am also wondering how the OP was pushing a 85 grain Nosler at 3700 out of his 25-06. I get good accuracy with the 85's with RE 19, 56.5 grains, runs around 3550 fps. In four rifles this is a good load, and is close to max buy the way the primers look.

The OP states his drop charts are wrong, it could be that he's not shooting as fast as he thinks. Just an observation.

I have Brian's book, but I'm not ashamed to say reading it gives me a headache. Just too tech. in a lot of ways. SO... Keep it simple.

Don't ask me to explain it - I never said it would.

There are those that claim that their rifles shoot smaller groups (in moa) at long range... based on one group.

I do a lot of testing of loads - typically 16 hours a month when the weather is good - I have often had a rifle shoot smaller group (in moa) at long range than it should based on the 100 yard group... but like anyone's "braggin' group" it is not repeatable.

To make a case for a rifle that shoots smaller groups at long range, you must be able to do it over and over... which no one can.

Sierra has a 300 yards under ground range, and back 7 or 8 years ago, I called the head of bullet testing about something else, and while I had him on the phone, I asked him about this small group at long range "theory" (they use guns mounted on concrete blocks), and he laughed.

 

[ninehorses]

I played with tops as a kid, the longer they spin, the more they wobble.

Sorry, I added to my post a little while you were answering.

 

[orkan]

Originally Posted By: CatShooter
To make a case for a rifle that shoots smaller groups at long range, you must be able to do it over and over... which no one can.
This is not true. I would ask you to re-evaluate your position.

I can take you out anytime you like, anywhere you like, with a .375CT, and show you a 1" group at 100yds, that will stay a 1" group out to about 400-500yds. As I said, a group size which is smaller in linear distance is unlikely, but a group size which is smaller in angular units is very, very likely.

The longer the projectile, the more pronounced the effect. Hence why it isn't normally identified, and thus is completely dismissed by those whom have not spent a great deal of time with the larger cartridges. Yet when you are launching a projo which is 2" in length... things change.

I have no doubt that the same principles apply to shorter projectiles, yet it is harder to identify.

 

[CatShooter]

Originally Posted By: orkanOriginally Posted By: CatShooter
To make a case for a rifle that shoots smaller groups at long range, you must be able to do it over and over... which no one can.
This is not true. I would ask you to re-evaluate your position.

I can take you out anytime you like, anywhere you like, with a .375CT, and show you a 1" group at 100yds, that will stay a 1" group out to about 400-500yds. As I said, a group size which is smaller in linear distance is unlikely, but a group size which is smaller in angular units is very, very likely.

The longer the projectile, the more pronounced the effect. Hence why it isn't normally identified, and thus is completely dismissed by those whom have not spent a great deal of time with the larger cartridges. Yet when you are launching a projo which is 2" in length... things change.

I have no doubt that the same principles apply to shorter projectiles, yet it is harder to identify.


No need to re-evaluate anything... if that is your experience, then you have other issues. Parallax is the first to come to mind, but there are others.

Bullets do not travel that way.

But to be fair, I'll take you up on your offer...

"I can take you out anytime you like, anywhere you like, with a .375CT, and show you a 1" group at 100yds, that will stay a 1" group out to about 400".

... Ledyard Sportsman's Association, Ledyard Connecticut. Any Saturday you like.

As a side note, I am amazed.... I mean absolutely AMAZED... at the large number of shooters on the internet that have rifles that shoot 1" (1/4 moa) groups at 400 and 500 yards. I mean, that is getting very close, I mean within fractions of an inch, of being benchrest World Record performance.

Guys build $5,000 rifles that weigh 17 pounds, in exotic calibres, with 45X scopes on top, and they don't do that well...

I must be doing something wrong...

 

[scott2506]

Originally Posted By: CatShooter

As a side note, I am amazed.... I mean absolutely AMAZED... at the large number of shooters on the internet that have rifles that shoot 1" (1/4 moa) groups at 400 and 500 yards. I mean, that is getting very close, I mean within fractions of an inch, of being benchrest World Record performance.

Guys build $5,000 rifles that weigh 17 pounds, in exotic calibres, with 45X scopes on top, and they don't do that well...

I must be doing something wrong...

I doubt anyone is clamming they shoot 1 inch 400 yard groups "ALL THE TIME"
No one is claiming that they get this EVERY group.

Catshooter, I've personally seen you post your ultra rare 1/4 inch 100 yard groups on the net also also. A lot of people do it. It is not a bad thing to share some success.

Personally I'd rather have a gun that shoots 1/2 moa or less all the time, than one that shoots 1/4 moa part of the time and 3/4 MOA the other part.

I have shot 2 different 3 shot groups in a row at 200 yards that measured 0.500 inch and 0.495 inch with my old Factory 25-06 factory 26 inch bbl Ruger M77.
just 3 shot groups but it has 1400+ round down the tube and is quite burned out and I can not keep that up on average anymore, it used to be avg a 1/2 MOA gun.
I've shot 1.5 inch groups at 400 yards. It is not that hard. Can I average this? no! Last week I shot just one group at 401 yards, it messured 2 inches exactly or 1/2 MOA. LUCK? probably!
My 204 shoots a few 1/4 moa groups every time I go out, most are 1/2 moa or less but I admit some groups flyer open to 2/3 moa. I've shot a 3 shot group of 0.024 inch with it.. or 1/40th MOA at 100 yards.
I have bad eye's and I am not that good of a shooter at all either.

A lot of people here as well as the rest of the net can do much better than I can.. much better.

Some people don't have the mega dollars to to have $5000 17 lb guns with 45x scopes and exotic calibers, they are just born to be better shooters than you and I are.


Have a good day