How do you lower S.D.?

[Steve Shelp]

Steve,
My intent is not to get you all worked up but I just dont understand your viewpoint on chronographs.
A chronograph is a precise measureing tool used for hand loading ammunition, I can say the exact same thing about a powder scale. would you omit using a powder scale???? I'm betting that you use one.
So if a person wants to precisly measure what goes INTO a case, why would that person not want to precisly measure what comes OUT ????
It just does not make sense.
UB

I'm not riled up. I knew my position on this was opposite of what the majority on this site beleive. Not a problem in my book. The only reason I even said anything is going back to what the original poster said. That man said he was having trouble and is only shooting 1 1/2" to 2 1/2" groups at 100yds. He asked about working on his SD with a chrono and everyone started piling on with oh yea go for it. I don't beleive that this man's problem will be solved in any way, shape, or form by the use of a chronograph. He needs to get a couple cans of various powders(I suggested my 2 favorites for the 300 Win Mag) and a box of bullets, and various primers and go to the range with his loading gear. Do that right there and that will vield the biggest improveement in his accuracy right there. And should get him under an inch consistantly if himself and the rifle/scope combo are up to it. All without the use of a chronograph. How amny years have we all shot rifles and worked up loads BEFORE chronographs were cheap enough for the average man? You will never convince me that a chrono is an absolute must for load developement UNTIL your down into tweeking that last 10% were are all talking about. And even then I personally don't think its worth all of that. But to each his own there.

A chronograph is a precise measureing tool

when you are talking about the majority of chrono's used on this board that would not be an accurate statement. A 1' through 4' spaced chrono is a tool, but not a precision tool. Simple math and physics prove that. My PACT with a 2' spacing is a tool and I use it to show trends, but I don't believe for a second that the 2905fps veleocity it just reported to me is "precise". But you can see trends and that is all I look for.

I don't get into comparing who has the bigger chest of medals when it comes to competitions so I won't post what I've won over many years of playing this game. But I have my fair share of wins and top 10 & 20 placements on State and National level for 600 & 1000yd NBRSA and IBS matches. I placed pretty well in HG last year at the IBS 600yd Nationals and that rifle/barrel has never been fired over a chronograph. I could not tell you my velocity let alone the SD. But the (8) 5 shot targets averaged 2.9" over a 2 day span in the South Dakota "breezes". And I didn't spend 100ss of rounds doing load testing either. My load testing consisted of (3) 10 shot groups the weekend before that at the 1000yd Nationals in VA. Before that weekend that was a brand new barrel/throat.

I hope this gentleman get his rifle figured out. That is what this thread is suppose to be about.

J E Custom has some merit to his post. One statement in his post is worth its weigh in gold... "By the way after I started using this method I went back and tested all of my best loads for SD and found them all to have very low SD,s. many were in the single digits (best was a 1000yrd load @04 in 5 rounds."

That is what I said in my first post. The paper will tell you when it's working and I have never spent hundreds of round in load developement for any rifle. A good group HAS to have good numbers across the chronograph. Or it simply won't group to begin with. But I have perosnally seen more than once, loads that had great SDs across the chrono but wouldn't group in competition at long range. The example I mentioned above about my HG with the 338 barrel on it. VV N170 and Fed 210 would give single digit SDs and group good at 100yds. But it shot all over the place at 1000yds. I could put R25 back in that case (R25 would easy double the SDs of the VV N170 load) and it would go down to 8" gun shooting rounds groups.

Now if you really want to tell stories to raise some eyebrows, I know a very prominate long range BR shooter that is one of the premier long range gunsmiths in the industry that does his load developement using 2 shot groups to start out with. It works for him. But that isn't for this post.

After all,isn't that what makes tight groups,CONSISTANCY.

Yes Sir! And your load gives you that consistancy, not the chrono. So work on your load. The chrono only reports back your consistancy as accurately as it was designed for. Paper targets don't lie. Good luck with your new Savage. I'm sure you will be much happier with that rifle.

Steve

 

[squirrelduster]

Jim at R.W. Hart just gave me a recipe for a great load. I was shooting Nosler Brass out of my 300 with federal 210 primers 73.5 grains of Reloader 22 over a 190 Berger VLD. Shot a .328 group right out of the gate.
When I started I was in the same boat you are with the 1 1/2 to 2 inch group. I was ready to ship the rifle off for a new barrel but I was able to work up a load with IMR 4831 that shot a .381 3 shot group. (.689 outside spread - .308?)
I am not a target shooter, I don't have the equipment for competition or to be really accurate. I use a tackdriver front bag and a cheapo rear. I have a 6br that shoots a bunch of different bullets and loads really well making a nice ragged hole at 100 yards but the 300 is much more picky.
Try the RE22 and the 190 VLD load and let us know what happens. My brother has tried the same load with the 180 accubond and had great success also. We were shooting golf balls at 120 yards. The 300 is a little overkill for the golf ball but pretty cool when hit.

 

[squirrelduster]

Jim at R.W. Hart just gave me a recipe for a great load. I was shooting Nosler Brass out of my 300 with federal 210 primers 73.5 grains of Reloader 22 over a 190 Berger VLD. Shot a .328 group right out of the gate.
When I started I was in the same boat you are with the 1 1/2 to 2 inch group. I was ready to ship the rifle off for a new barrel but I was able to work up a load with IMR 4831 that shot a .381 3 shot group. (.689 outside spread - .308?)
I am not a target shooter, I don't have the equipment for competition or to be really accurate. I use a tackdriver front bag and a cheapo rear. I have a 6br that shoots a bunch of different bullets and loads really well making a nice ragged hole at 100 yards but the 300 is much more picky.
Try the RE22 and the 190 VLD load and let us know what happens. My brother has tried the same load with the 180 accubond and had great success also. We were shooting golf balls at 120 yards. The 300 is a little overkill for the golf ball but pretty cool when hit.

 

[goodgrouper]

So if a person wants to precisly measure what goes INTO a case, why would that person not want to precisly measure what comes OUT ????
It just does not make sense.
UB

Exactly.


I'll give two bits to the person who can tell me who it was that said, "the two most important tools to the rifle shooter to ever come along are the chronograph and the borescope".

Let's examine why this person would say this. Until the invention of smaller, cheaper, personalized chronos were made available, the reloader could only "paper tune" like what this Steve Shelp does. This works-to a degree. But the chronograph speeds up (no pun intended) the load development process by a factor of 10. Leaving the chronograph out of 90% of the development process and using it for the remaining 10% is backwards and I will tell you why. CHrono's tell you much more than the speed of your load. They also show you pressure curves, load nodes, minimum and maximum sweet spots, maximum pressures, minimum pressures, average velocities, load uniformities, effects of neck tension, effects of bullet seating depths, effects of new lots of powder in conjunction with burn rates, effects of different primers, bullet jacket differences, and so on. Shocking isn't it?

For the "paper puncher" who knows exactly how far his target is and gets basically limitless sighter shots to adjust, even knowing the most basic thing as average velocity is meaningless. But to the long range hunter (which is what this site is all about) he needs to know how fast his ammo is to formulate a correct drop chart. That right there all by itself warrants a need for a chrono. I usually take TWO chronos to the range to get an idea of what the bc of a bullet is out of that particular gun (as they are all slightly different) and I very rarely shoot at 100 yards WITHOUT a chrono. About the only time I do is when I am practicing for short range comp with my 6ppc. But I still chrono it when developing a load because I have found that loads with better sd's stay more accurate over a wide variety of conditions than loads that don't. But as Steve says, the group on the paper is all that matters. But what I'm saying is that even with a 6ppc, a chrono sheds light on things that PAPER SIMPLY CANNOT AND WILL NOT EVER TELL YOU! And things get even more amplified at distance.

I have probably made more factory rifles legitimate 1000 yard shooters than any 20 benchrest shooters have medals in their trophy room and that process would not be possible without a chronograph. Period. Show me one custom gun that was paper tuned and was accurate and I'll show you a dozen sub par guns that were made 1k accurate with the help of a chronograph. My point is that it is much easier to make a custom gun shoot at 1k by paper tuning than it is to make a sub par factory gun shoot 1k without a chrono.

But I do agree with this Steve fellow on one account. Not all chronos are created equal. Perhaps if he had bought a decent chrono that actually was accurate, it wouldn't have skewed his perception of them. A 2' space inbetween two skyscreens is mathematically inferior by design. But, get three skyscreens spaced on a 4' or 8' rod a proof channel and the accuracy of the readout is improved. This is of course the Oehler 35 and that is why most component manfucturers use it. That is also why the military uses it and why a civilian can no longer buy one (at least through 2010).

Another point while I'm at it:
The quickest way to change the standard deviation in a load is to change the charge weight. Throwing a new primer in the mix to get a different sd can be done but is a bigger pain than just going up .5 grains in weight.

OK, another point. This one goes out to the Yaw of repose unbeliever:
YOU ARE WRONG! There has been literally thousands of test and studies done on this point and they all have documented it quite well. Just because you have failed to do research on it doesn't mean the reasearch doesn't exist!
EVERY BULLET OUT OF EVERY GUN YAWS WHEN IT SLAMS INTO THE ATMOSPHERE! SHort ones, long ones, arrows, everything yaws unless it is shot in a vaccuum. If you grasp this concept, you will quickly see that if the target is close enough, every bullet will show inaccuracies due to yaw. Some just dampen the yaw quicker than others and if the target is past where it dampens, all looks and shoots well. But don't think that another bullet has dampened at that same distance particularly if it is a longer bullet. It will take the longer bullet more distance to dampen therefor giving better accuracy at longer range.
IF the dampening of the yaw of repose didn't exist, every bullet out of every gun would go through a paper target off point because every bullet has initial yaw. DOn't believe me? Pick up a copy of RInker's "Understanding firearm ballistics" and flip to the whole chapter that covers this. Or go to youtube and watch slow motion photography of a 30" arrow yawing so bad that it looks like it is going to fly into the floor and break in half until it gets about 10 yards away from the bow and suddenly flattens out and flies straight.

I think where a lot of these non-believers get ruffled about this subject comes from a misunderstanding of terminology. When we say the long bullets shoot better at distance, we are saying they shoot SMALLER MOA, NOT SMALLER GROUPS. Or in other words, a gun that shoots 1" at 100 yards can shoot half MOA at 300 yards. That would of course be a group of around 1.5" so you can see the group didn't actually get smaller, it just shot better MOA downrange because the bullet finally stabilized and followed it's nose.

Anyhow, I have deviated from the sd question a bit but I hope this makes things clearer. Striving for a better SD is not just a good idea, it is paramount to consistent long range success. Whether you choose to find it by paper tuning or by using a chrono is totally up to the shooter but I guarantee you that one is faster (again, no pun intended) and gives you much more detail.

 

[Steve Shelp]

Ok. now the rules have changed. Goodgrouper what you are talking about is a ballistics lab. I have access to and use an Oehler M43 with the accoustic screens with 300yds of cable. So no I'm not naive in purchasing my equipment. We used the M43 for the experiements several years ago to show BC variations of non-cut meplats, cut meplats, and tipped bullets. But an M43 isn't the average chrono that the majority of people own.
This thing is going way askew with everyone interpeting stuff from so many angles that this can go on forever. Like I said I'm no trying to win a popularity contest, just trying to help out the original poster. And a chrono isn't the solution to his problem. After reading his last post I beleive trading for the Savage is a great step in the right direction.

As for your little cheap shot at paper punchers and your so called magic with factory rifles I'll leave that alone. You can beat your chest behind your keyboard. But suffice it to say that I've tuned a few rifles in my life also. I'm not getting into a #$@% contest.

Everyone can believe what they want and have fun doing it and leave it at that. So I'll close with one more point that I have made in every one of my posts that speaks volumes and applied to the original question posed in the first post. To quote yourself....

"The quickest way to change the standard deviation in a load is to change the charge weight. Throwing a new primer in the mix to get a different sd can be done but is a bigger pain than just going up .5 grains in weight.

Exactly what I have been saying!! You want better grouping from your rifle... work on your load! That is where you make your money in load developement. And it doesn't take a chrono to do that.

Steve

 

[goodgrouper]

I have access to and use an Oehler M43 with the accoustic screens with 300yds of cable. So no I'm not naive in purchasing my equipment. We used the M43 for the experiements several years ago to show BC variations of non-cut meplats, cut meplats, and tipped bullets.
Steve

Steve,
Having access to a nice chrono and actually using it for it's intended purpose are two different things.
No one is changing the rules here either. However, you are changing your story a bit. At first you say you have a lesser chrono that is inaccurate, then when I point out the short comings of it you automatically switch to the Oehler 43 as your alibi. Interesting. But from the way you speak, you only used it once and it was several years ago?

As for your little cheap shot at paper punchers and your so called magic with factory rifles I'll leave that alone. You can beat your chest behind your keyboard. But suffice it to say that I've tuned a few rifles in my life also. I'm not getting into a #$@% contest.

No cheap shot at paper punchers. Perhaps you didn't read that part where I said I was a paper puncher too. But I am realistic about paper punching. It is not the end all be all of load development because it is shooting at known, even distances and usually includes custom equipment which is much easier to work with. You are the one who brought up paper punching in a somewhat condescending manner to try and intimidate others into believing your POV. It doesn't work with me because I am also a 1k paper puncher (and further) and a long range hunter and I develop loads for factory rifles that kill game at long distance. So I do two more things than you do and I do them with the help of a chronograph. This is not beating my chest, it is called supportive argument details.

Exactly what I have been saying!! You want better grouping from your rifle... work on your load! That is where you make your money in load developement. And it doesn't take a chrono to do that.

I have a question. You say that you "work" on your load and you change the sd by going up .5 grain in weight. But if you aren't shooting through a chrono when you do this, how do you know if you improved your sd on that load? The paper ain't gonna tell you that the .5 grain you added reduced your sd from 15 to 5. Only a chrono can do that!
Steve, I am sorry but you still simply aren't getting what the majority of the posters in this thread are telling you! We are saying that you work on your load with the help of a chronograph! I don't see what is so hard to understand here. The chrono is a tool to help in load development, not just a gadget to use in isolated experiments once in a blue moon.

 

[Boss Hoss]

GG got to admit you hit this one spot on....

 

[Weda]

Dave,

Interesting. That explains things a bit better, or at least draws a realtionship i can relate to.
In therory wouldn't there be oval holes in the paper then?

Boss, I don't shoot from a bench. Come to the Whittington Center and run the "Sporting Rifle Match" with me.

 

[Boss Hoss]

I will be in Raton shooting some NBRSA 1K this year. Will also be taking a 2 week course at Trinidad the last 2 weeks of June for fun and will be bringing a few toys with me...

 

[Weda]

Boss,
Since I have the opportunity, these days I thought I might try 1K br. Who know it might happen this year.

I have a membership to CRC if you want to practice without paying at Whittington. Be glad let you in under my family membership.

Dave,

Using your analogy, it is f'ing amazing we can drive a bullet to hit where we want. My wife understands the physics thing a weee better than I do.

 

[Reloader]

Bullet yaw is a myth.

This is not to flame anyone, just to state some facts:

Spinning tops have absolutely no validity when we are talking bullets. A spinning top "goes to sleep" in a different spot every time.

A large grouping load can NOT get smaller at longer distances, it is physically impossible. Simply put, a bullet leaves on a path once stabilized and only is effected by the atomosphere in which it flys(IE: wind, pressure, gravity, etc).

Some bullets will leave a bbl unstabilized and can become stabilized during flight, once they become stabilized they fly on that path only effected by the atmosphere and elements apllied. These unstable bullets do not magically go back to the path the shooter wants them to like some sort of guided missle.

This is an old myth and is not true, the laws of physics will not allow it.

Sorry to burst some of you fella's bubbles,

Reloader

 

[Weda]

aww crap.. see this is my point..

lotsa people out there saying it but no proof.

UncleB.. got pics of oval holes at 100 and round ones at 500?

That would proove it.

Amazing we can even drive a bullet straight with all that happens.

 

[Buffalobob]

Post #1 - Yaw

Sierra ballisticians wrote a book called Exterior Ballistics and it can be found online. If my memory serves me correctly they are also the principal authors of one of the more popular ballistics calculators that many of us use.


exterior ballistics

2.4 Lessons Learned from Ballistic Coefficient Testing

The coning motion caused by the initial yaw of a bullet when it exits the muzzle generally damps out as the bullet flies — that is, it decreases in amplitude as the bullet travels downrange. This is because the causes of initial yaw are transient in nature. In other words, these causes occur only at the muzzle and do not persist as the bullet flies. Also, the aerodynamic forces caused by the coning motion are restoring forces (tend to improve stability of the bullet) as long as the amplitude of the coning motions is not large enough to cause loss of stability (tumbling). This is the fundamental cause of many anecdotes heard by these authors that "my rifle shoots 1.5 MOA groups at 100 yards, 0.8 MOA groups at 200 yards, and 0.6 MOA groups at 300 yards." However, some causes of coning motion are not transient in nature, and can cause sustained coning motions throughout the flight of the bullet. Any imperfection in bullet structure leading to a small center of gravity offset from the bullet longitudinal axis can cause sustained coning motions of the bullet as it flies. Also, any small aberrations in bullet shape, such as a small imperfection in point shape or tail shape, can cause sustained coning motions as the bullet flies. This a very strong reason to shoot bullets of high manufacturing quality.

Perhaps there were never any dinosaurs and certainly I have never personally seen one but there seems to be a lot of "indirect evidence" that they existed.

 

[goodgrouper]

This is not to flame anyone, just to state some facts:

Spinning tops have absolutely no validity when we are talking bullets. A spinning top "goes to sleep" in a different spot every time.

A large grouping load can NOT get smaller at longer distances, it is physically impossible. Simply put, a bullet leaves on a path once stabilized and only is effected by the atomosphere in which it flys(IE: wind, pressure, gravity, etc).

Some bullets will leave a bbl unstabilized and can become stabilized during flight, once they become stabilized they fly on that path only effected by the atmosphere and elements apllied. These unstable bullets do not magically go back to the path the shooter wants them to like some sort of guided missle.

This is an old myth and is not true, the laws of physics will not allow it.

Sorry to burst some of you fella's bubbles,

Reloader

Umm, how can I say this tactfully? This above post is the most incorrect, untrue, misinformed post I have seen since I have been visiting this site for 4 years and I am here to tell you I have seen some doosies. Posts like this is why I had to put the quote from Albert Einstein in my sig line. The fact that this post was posted in what I assume was all seriousness is almost beyond belief. Seems like every couple of months, someone somewhere gets on this site and starts up this debate over nothing. The facts are so well documented that it really makes the new guy look stupid for even debating this topic. Even the most unread armchair theorist in the world would have to, at some point in his life, stumble upon the research of this topic. And if not, here is just a sliver of some so you can no longer use ignorance as an excuse. Not to burst your bubble or anything but here she goes:

And I quote from Robert Rinker's book, Understanding firearm ballistics chapter 8 page 95 paragraph 4:

"[talking about gyroscopic stability]There are several methods of proving this is fact rather than theory. Of course, Gyroscopes have been studied in laboratories since at least the early 1800's. Bullet's flight paths have been examined extensively. ONe of the more modern methods is by special photographs and spark shadowgraphs, which show the attitude of the bullets as well as its place in space and time. THis is limited to only the best laboratories.

page 95 paragraph 7
Even a bullet that will quickly stabilize may leave the muzzle at a yaw as much as 5 degrees. Testing of .30 caliber match ammunition showed 4 nutations and .68 of a precession in the first 48 feet of the muzzle. That is typical. There are usually several nutations for each precession. The nutations are usually in the form of loops that pass through zero yaw. As we said earlier, this produces the path of a helix with flat spots.

page 96 paragraph 2
There will be a slight yaw and unbalance while the bullet is still in the bore. The confinement is relieved at the muzzle and the bullet departs in a slight yaw. This may be as small as a degree or two in a good barrel with the correct twist for the cartridge. Even a bullet that will become stable can have an initial yaw of up to 5 degrees. Yet a beginning yaw of as little as a degree or two can have a substantial influence. The yaw may be extremely high with the use of poor and mis-matched equipment. In any case, the force on the bullet is not on the bullet's center of gravity, but in front of it. As discussed, this force will try to tumble the bullet. The initial yaw outside the boreand the helix lead angle follows this interrelationship.

page 96 bottom paragraphs
The initial yaw as the bullet leaves the muzzle is governed mostly by stability. The direction of the yaw is haphazard or random and can be anywhere around the 360 degree of the muzzle. This makes target dispersion larger in cases of considerable yaw with low stability.

Penetration tests conducted by the U.S. army have shown less penetration at very short range than at moderate range. The lack of expected penetration at short range is blamed on initial yaw, which prevents the bullet from striking straight on. When the bullet stabilizes, the depth of penetration increases. Then the penetration gradually drops again as velocity, energy, and momentum decrease with extended range. The initial wobble that is yaw and precession can last up to 200 yards before settling down.

Page 98 bottom paragraph
Summary. To reiterate, yaw and nutation are different. Nutation is gyroscopic in origin and very small. Yaw is larger and while not cause by the same gyroscopic action, it still has gyroscopic relationship. Both are affected by precession and interact together. If the bullet is not moving through the air exactly point on, for whatever reason, then the pressure is not through the center of gravity but before or ahead of it. This creates an overturning or upsetting action, which because of precession has a result 90 degrees from where it is expected. Further, the high speed of rotation is constantly changing the direction of the upset, but always 90 degrees from the force.


END QUOTE


Rinker than further goes into detail about spinning tops and has the math to show that they and aeronautic gyroscopes obey the same laws of physics as bullets and so on and so forth just as Dave Wilson was trying to explain.

Hope this clears it up again. I guess I need to just keep these pages on file so I don't have to keep typing this up the next time we get someone on here who doesn't know which end of the gun the bullet comes out of. Sorry for the grumpiness, I just get so **** tired of people trying to dispute the facts to confuse others who are trying to learn the science.