ES and SD

[williada]

Dave we are singing the same tune but that might be confusing to others because we are approaching this from different directions. I entirely agree that extreme spread will be good at explaining what has happened, but personally, I would qualify that SD will tell you what to expect which might be confusing to some. It is because the rifle must be in tune and that being a normal distribution to which you can statistically apply SD figures. Because you guys have done a large sample then we would also be confident to use the figures you produced knowing the rifles were reasonably tuned and were not dud barrels. That is great work. But it’s harder work to find a suitable barrel that is reliable and very accurate of international standard. If we are using the data from elite shooters with proven barrels perhaps the data set is unique compared to the average shooter.

New barrels have a speed hump before their velocities stabilize in most cases. Load development has to bear this in mind and not wear out the barrel chasing an SD too early. That’s why I use a staged group analysis as a guide before refining things with regards to a barrel’s personality.

I also think it is necessary to map velocity against elevation at 1000 yards once the barrel is specially tuned not before. One of the members of the development group has recently confirmed that prediction at Belmont which a few discussed last year after being belted in the Queens. I know they used a lower velocity range and the quality of the people commenting do use SD in their load development.

You may know I have been receiving scanned groups for analysis from a few in a development group and from around the country to determine if a barrel is suitable and to examine what its personality is. We have had to modify the tunes to get the most out of some of them and these are suspect at long range as shown by results because there are simply different tunes more responsive to SD. The modified patterns of neutral and negative profiles may hold up at 1000 yards with a low SD but from what I have seen, the underlying personality comes out with small environmentally induced velocity change for better or worse.

I suggest a tune that is manageable in its weakest area yet hold at 1000 yards. You just have to examine Alan’s figures of past Queens and past 700 yards to see where the trends lie across the competitors with regards to score something can be improved yet anecdotally we know SD is really worked on by competitors.

May I also say, the Magneto speed is a no, no because an 8 oz weight will alter your launch angle when it is off the barrel and change your group from what I have seen.

What we Southerners experience, is all seasons in one day, so staying close to that velocity spread is sometimes impossible. The tune is out the window if it is nodal. I remember James C being blown away in Malaysia with elevation in the Commonwealth Games with a tuned rifle that was subject to extremes between the morning and afternoon. What sort of tune?

The problem for many shooters is they cannot afford to keep changing barrels to get a barrel that will meet international standards. I would think you would have to evaluate quite a few and that’s the hard part if people don’t know what to look for.

[DenisA]

Whats better than 1 Dave... 2 Daves!! now my head will really explode...

Most current F-class shooters will pick known good components to begin with and pretty much most loads are made of a common recipe. In the case of a .284W, Lapua, Bergers, Federal GM210M and ar2209.
Assuming that all case preparation is careful and uniform, we've found our hottest node at 2820fps and the tightest SD of 10 is central to the node. Whats the next step to reducing that? I'm assuming it's trying different primers (or weight sorting them)or powder, but then how many rounds or what % of accurate barrel life do we use in development, what level do we accept before the testing ends and for what level of competition. Club shoots, PM's, Queens and International?

If you have a great load with low ES and SD and you have a tuner on the barrel, adjusting the tuner will change the group shape and size but will it change the ES and SD?

Does reducing ES and SD reduce the effectiveness of a positively compensated load? Is it a case of having to choose which method of the 2 you want to achieve LR accuracy (if you have a positive trending barrel)?

[plumbs7]

Whats better than 1 Dave... 2 Daves!! now my head will really explode...

Most current F-class shooters will pick known good components to begin with and pretty much most loads are made of a common recipe. In the case of a .284W, Lapua, Bergers, Federal GM210M and ar2209.
Assuming that all case preparation is careful and uniform, we've found our hottest node at 2820fps and the tightest SD of 10 is central to the node. Whats the next step to reducing that? I'm assuming it's trying different primers (or weight sorting them)or powder, but then how many rounds or what % of accurate barrel life do we use in development, what level do we accept before the testing ends and for what level of competition. Club shoots, PM's, Queens and International?

If you have a great load with low ES and SD and you have a tuner on the barrel, adjusting the tuner will change the group shape and size but will it change the ES and SD?

Does reducing ES and SD reduce the effectiveness of a positively compensated load? Is it a case of having to choose which method of the 2 you want to achieve LR accuracy (if you have a positive trending barrel)?

First up !what a great couple of threads! Ive been enjoying them!

I hear up in Banana country in NthQld a certain buch of hillbillies ( I mean that affectionately) have their Sd's down to 2 ! But don't quote me on that as the source was from a very shady Nsw man and we just won the first game of state of Origin! So he could've been telling me a few porkies !
I think our Captain just spelled it out to us teamies of where we should be with our loads .

I think with the testing ive done and most of it at 500m and some at a 1000 yds, I think a neutral tune and a good sd load are more idiot proof to changing conditions!
Regards Graham.

[jasmay]

Guys, here is my take on the average Joe tuning to the standard of the Williada's and Dave Mac's of the world.

1) its hard for shooters in their infancy (I put myself in this group, 4 years target shooting and a couple of decades of bush bashing, 2 medals from the worlds and many others from queens and a brain wondering if this is all a fluke) to know if position is right, recoil control is consistent cheek weld etc etc. and is not contributing to elevation errors as well as managing what ballistic influences are doing. How these things are approached and handled can be quite crippling mentally for some this forum at times is a classic example of.

2) there is no "Go To" method for load developing, most people have different methods and this is seen even with the guys who are consistently at the top, what we are fed is quite often just a piece of the puzzle which as can be seen in an absolute plethora of threads on here and other forums just adds to frustration and confusion for many

3) there is no coaching program for shooting, little lone loading for developing a rifle capable international standards.

Imagine the above and how a new shooter to the line must feel.

Id love to see a coaching system developed over time and implemented at the club level in the future.

[williada]

Plumbs to be frank, loose lips sink ships. There is some additional information to be shared locally for the average shooter to improve their skills to push our elite shooters further so they can not relax on their laurels and enable the average Joe to get more from the sport, so that they become more involved in the sport. But this was being made locally for good reason. Its no help to people's team mates if people say what works or doesn't work in view of an important competition. People may lose their trust because some are not as discrete or smart enough to know the position they put themselves in that annoys others trying hard to do well too. That is not good for team harmony, and in the past, I have seen people miss team selection irrespective of how well they can shoot.

So I will not comment further as to the detail in group analysis except in a private setting where all participants can follow the procedures, and not half-baked approaches where hearsay or "Chinese whispers" develop and the essence of the exercises are lost.

If you are comparing something then apples must be compared with apples, not other fruit. If you are comparing tunes, then normal distribution of results should be based on nodes rather than independent velocities which may be skewed or suffer from kurtosis as statisticians put it, in their use, to evaluate the dispersion of data. Its knowing that part that finds you the best place to be.

[plumbs7]

Yes David , I think ur right maybe we are sharing too much here ! And I don't know if sd of 2 is even possible ! It's most likely akin to the D day landings 1944 and the red herrings fed to the Germans and Roswell alien ufo crash of the 60's . So don't read too much into it !

Jason I'm confused so for a newbie yep they must think we are a little crazy!

[mike H]

Plumbs to be frank, loose lips sink ships. There is some additional information to be shared locally for the average shooter to improve their skills to push our elite shooters further so they can not relax on their laurels and enable the average Joe to get more from the sport, so that they become more involved in the sport. But this was being made locally for good reason. Its no help to people's team mates if people say what works or doesn't work in view of an important competition. People may lose their trust because some are not as discrete or smart enough to know the position they put themselves in that annoys others trying hard to do well too. That is not good for team harmony, and in the past, I have seen people miss team selection irrespective of how well they can shoot.

So I will not comment further as to the detail in group analysis except in a private setting where all participants can follow the procedures, and not half-baked approaches where hearsay or "Chinese whispers" develop and the essence of the exercises are lost.

If you are comparing something then apples must be compared with apples, not other fruit. If you are comparing tunes, then normal distribution of results should be based on nodes rather than independent velocities which may be skewed or suffer from kurtosis as statisticians put it, in their use, to evaluate the dispersion of data. Its knowing that part that finds you the best place to be.

Williada,
I think it is time to tone this discussion down as you said,in my speak,put a sock in it.Honestly,I was beginning to think people are drinking their own bath water.Next thing we will be told that sun spots and solar flares are the cause of wild shots. Technology can go so far,temperament is vital and just as important.
Mike.

[DaveMc]

I don't think there needs to be a kybosh put on this conversation. There is no secret stuff here and in fact I think it is rather important for a lot of shooters (new and old) to get their head around this. I will ask to (please) leave the compensation discussion out of it though and reserve that for another topic. It is a large discussion in itself that needs time and data and can confuse the matter for most. The original Post asked "what ES and SD" do we aim for to achieve good results for 1000 yards and I believe we are in a good position to answer this. I agree wholeheartedly though that what I am discussing is "in tune" rifles and said same midway through my first post. - I define "in tune rifles" to be those tuned to hold good short range groups for a given velocity range.

So in line with Williadas comments - I believe velocity sd is the best predictor of vertical spread for "in tune" rifles (ignoring compensation). Most of the data we have plotted for rifles at long range follows a "normal distribution" very well and when you unwind the predicted velocity effect on each shot you would be surprised how flat the groups become!! ES will vary more from group to group especially in small sample sizes - it also tells you little about shot to shot consistency. It does help explain the extreme edges of your group though.

So, if you have your load tuned well at short range (say under quarter minute elevation) and want to have a rule of thumb prediction of how you will go at 1000 yards then these figures work reasonably well with many basic assumptions (and Good Conditions!!).

you have a velocity sd in the 2's over a 10 shot string (12 but cut the first 2 to give you a better reading of what your barrel does when it settles in). Yes, this is achievable and repeatable if you are lucky enough to score a hummer barrel and have all your loading techniques down to a fine art- We have seen a few barrels produce this in our testing now). then you will "expect" 1 shot in 20 to be +/- 4 to 6 fps and in good conditions your rifle will hold excellent elevation at all ranges from 100- way past 1000. Poor sighting (mirage), fluctuating heat and wind etc will detract from this so that in the real world groups are larger than what your rifle and loading can achieve. Also we all "enlarge" our groups by winding to the centre - unless you are lucky enough to land smack on in first shot. This also enlarges elevation so you need to unwind the sight settings before analysing 1000 yard plots or looking critically at elevation in a match environment.

sd 5: expect 1 or 2 to be +/- 10 fps over 20 shots and starting to push the odd shot high or low in the 6 ring but most in the centre. Really a very good result and good enough to score well and be competitive in F class. 1000 yard BR groups are likely to be not quite in the game though with a few good 5 shot groups as don't forget, the bulk of our shots lie near the centre in a normal distribution.

sd 8 - mostly holding the 6 with the odd excursion out - can hold the competition in rougher conditions

sd 10 + - well good luck in todays game as you will be losing a few to elevation at the longs so are playing catchup from the start... You may still get the odd good 1000 yard score but if you are competeing regularly at the longs it will be frustrating

NB
** For a 308 lobbing in 230's the velocity sd's required are significantly tighter (around 2/3- 3/4!!!) for same elevation.
*** Not all barrels are as good as each other and w can put the same ammo in two barrels and get quite different results. Don't burn out your barrels testing

[jasmay]

I don't think there needs to be a kybosh put on this conversation. There is no secret stuff here and in fact I think it is rather important for a lot of shooters (new and old) to get their head around this. I will ask to (please) leave the compensation discussion out of it though and reserve that for another topic. It is a large discussion in itself that needs time and data and can confuse the matter for most. The original Post asked "what ES and SD" do we aim for to achieve good results for 1000 yards and I believe we are in a good position to answer this. I agree wholeheartedly though that what I am discussing is "in tune" rifles and said same midway through my first post. - I define "in tune rifles" to be those tuned to hold good short range groups for a given velocity range.

So in line with Williadas comments - I believe velocity sd is the best predictor of vertical spread for "in tune" rifles (ignoring compensation). Most of the data we have plotted for rifles at long range follows a "normal distribution" very well and when you unwind the predicted velocity effect on each shot you would be surprised how flat the groups become!! ES will vary more from group to group especially in small sample sizes - it also tells you little about shot to shot consistency. It does help explain the extreme edges of your group though.

So, if you have your load tuned well at short range (say under quarter minute elevation) and want to have a rule of thumb prediction of how you will go at 1000 yards then these figures work reasonably well with many basic assumptions.

you have a velocity sd in the 2's over a 10 shot string (12 but the first 2 t give you a better reading of what your barrel does when it settles in). Yes, this is achievable and repeatable if you are lucky enough to score a hummer barrel and have all your loading techniques down to a fine art- We have seen a few barrels produce this in our testing now). then you will "expect" 1 shot in 20 to be +/- 4 to 6 fps and in good conditions your rifle will hold excellent elevation at all ranges from 100- way past 1000. Poor sighting (mirage), fluctuating heat and wind etc will detract from this so that in the real world groups are larger than what your rifle and loading can achieve. Also we all "enlarge" our groups by winding to the centre - unless you are lucky enough to land smack on in first shot. This also enlarges elevation so you need to unwind the sight settings before analysing 1000 yard plots or looking critically at elevation in a match environment.

sd 5 +/- 10 fps over 20 shots and starting to push the odd shot high or low in the 6 ring but most in the centre and really good enough to score well and be competitive.

sd 8 - mostly holding the 6 with the odd excursion out - can hold the competition in rougher conditions

sd 10 + - well good luck in todays game as you will be losing a few to elevation at the longs so are playing catchup from the start... You may still get the odd good 1000 yard score but if you are competeing regularly at the longs it will be frustrating

NB
** For a 308 lobbing in 230's the velocity sd's required are significantly tighter (around 2/3- 3/4!!!) for same elevation.
*** Not all barrels are as good as each other and w can put the same ammo in two barrels and get quite different results. Don't burn out your barrels testing

Hi Dave,

Can I ask, at what weight projectile do you start to see a need for tighter SD's begin to arise? What do you think might be the cause of this?

[Matt P]

I don't think there needs to be a kybosh put on this conversation. There is no secret stuff here and in fact I think it is rather important for a lot of shooters (new and old) to get their head around this. I will ask to (please) leave the compensation discussion out of it though and reserve that for another topic. It is a large discussion in itself that needs time and data and can confuse the matter for most. The original Post asked "what ES and SD" do we aim for to achieve good results for 1000 yards and I believe we are in a good position to answer this. I agree wholeheartedly though that what I am discussing is "in tune" rifles and said same midway through my first post. - I define "in tune rifles" to be those tuned to hold good short range groups for a given velocity range.

So in line with Williadas comments - I believe velocity sd is the best predictor of vertical spread for "in tune" rifles (ignoring compensation). Most of the data we have plotted for rifles at long range follows a "normal distribution" very well and when you unwind the predicted velocity effect on each shot you would be surprised how flat the groups become!! ES will vary more from group to group especially in small sample sizes - it also tells you little about shot to shot consistency. It does help explain the extreme edges of your group though.

So, if you have your load tuned well at short range (say under quarter minute elevation) and want to have a rule of thumb prediction of how you will go at 1000 yards then these figures work reasonably well with many basic assumptions (and Good Conditions!!).

you have a velocity sd in the 2's over a 10 shot string (12 but cut the first 2 to give you a better reading of what your barrel does when it settles in). Yes, this is achievable and repeatable if you are lucky enough to score a hummer barrel and have all your loading techniques down to a fine art- We have seen a few barrels produce this in our testing now). then you will "expect" 1 shot in 20 to be +/- 4 to 6 fps and in good conditions your rifle will hold excellent elevation at all ranges from 100- way past 1000. Poor sighting (mirage), fluctuating heat and wind etc will detract from this so that in the real world groups are larger than what your rifle and loading can achieve. Also we all "enlarge" our groups by winding to the centre - unless you are lucky enough to land smack on in first shot. This also enlarges elevation so you need to unwind the sight settings before analysing 1000 yard plots or looking critically at elevation in a match environment.

sd 5: expect 1 or 2 to be +/- 10 fps over 20 shots and starting to push the odd shot high or low in the 6 ring but most in the centre. Really a very good result and good enough to score well and be competitive in F class. 1000 yard BR groups are likely to be not quite in the game though with a few good 5 shot groups as don't forget, the bulk of our shots lie near the centre in a normal distribution.

sd 8 - mostly holding the 6 with the odd excursion out - can hold the competition in rougher conditions

sd 10 + - well good luck in todays game as you will be losing a few to elevation at the longs so are playing catchup from the start... You may still get the odd good 1000 yard score but if you are competeing regularly at the longs it will be frustrating

NB
** For a 308 lobbing in 230's the velocity sd's required are significantly tighter (around 2/3- 3/4!!!) for same elevation.
*** Not all barrels are as good as each other and w can put the same ammo in two barrels and get quite different results. Don't burn out your barrels testing

Hi Dave
Thanks, that answers my question.
Matt P

[AlanF]

Hi Dave,

Can I ask, at what weight projectile do you start to see a need for tighter SD's begin to arise? What do you think might be the cause of this?

Jason,

Dave will have a better understanding of why, but I can tell you that its not so much the weight of the projectile as the velocity. If you run a higher MV with any projectile, it will be less affected by vertical caused by MV variation (SD/ES as we're calling it here). And its not a linear relationship. If you increase velocity by say 5%, you can afford significantly more than a 5% increase in MV SD and achieve the same vertical accuracy. Its one of the few things that improves when you up your velocity. I'll give some examples with your projectile of choice if you like.

Alan

[jasmay]

Hi Dave,

Can I ask, at what weight projectile do you start to see a need for tighter SD's begin to arise? What do you think might be the cause of this?

Jason,

Dave will have a better understanding of why, but I can tell you that its not so much the weight of the projectile as the velocity. If you run a higher MV with any projectile, it will be less affected by vertical caused by MV variation (SD/ES as we're calling it here). And its not a linear relationship. If you increase velocity by say 5%, you can afford significantly more than a 5% increase in MV SD and achieve the same vertical accuracy. Its one of the few things that improves when you up your velocity. I'll give some examples with your projectile of choice if you like.

Alan

Interesting, I am shooting the 30cal 200hybrid

I've seen some incredible elevation with the 215's moving slower.

Thanks for the info Alan

[AlanF]

Interesting, I am shooting the 30cal 200hybrid

I've seen some incredible elevation with the 215's moving slower.

Thanks for the info Alan

Okay, I'm only guessing what your normal velocity and MV SD are. Hopefully the following range of figures will cover your MV at least.

If you run the 200s at 2600 fps with a SD of 5 fps then that will be enough to hold the 6 ring at 1000yd for 99.95% of your shots (N.B. due to MV variation alone). Now lets say you run them at 2800 fps, your SD can relax to 6.4 fps without losing vertical accuracy. You can extrapolate for other velocity figures in this region with minimal error.

If you look at those figures, for an 8% increase in velocity, you can relax your SD by over 20% without losing accuracy on the 1000yd target. So as I mentioned earlier, its significantly better than a linear relationship.

[Brad Y]

Not to stir the pot, and I know competitive shooters probably dont like letting on everything, but what about those 1000yd shooters in the states that claim not to bother with chronographs and have likened trying to focus watching ES and SD in loads to say trying to get blood from a stone when trying to shoot small groups. I agree with Dave when he talks about barrels shooting small numbers. Havent been able to get them down yet to anything like what has been said but very impressed with how my barrels have shot- Williada you will probably have a decent explanation for this- assuming its how its been tuned?

[DaveMc]

Brad - it isn't stirring the pot and is a valid discussion - What I would like to do though is start another topic to run in conjunction with this. Otherwise it will lose focus. I haven't been able to participate much on the forum lately but feel it is time to put a little into this and the compensation/1000 yard tuning threads as there has been a lot of activity over last 12 months down this line.

So once again - This is based on the assumption you have a rifle tuned to short range accuracy - not one tuned for compensation at 1000 yards (which will have significant elevation issues at short range). In either case I would like to deal with fact, real targets, measured velocities vs impact on appropriate (accurate enough) gear and appropriate modelling in a scientific manner.

Alan/Jas, I will post a table/graph shortly that shows this relationship with a few common 308 projectiles. We have written a few pieces of valuable software and simulators.
Firstly a comparison simulator similar to the one Aubrey pointed to earlier for analyzing these types of effects on the target and will ask Alan to post a link to the latest version again please? (modified one - only have the original "twintarget").
Secondly Peter has written some software for unwinding scope adjustments and vertical components. He was in the middle of modifying the ballistics in that program to fit with the discussion we are currently having when he took a turn so the ballistics in the software are close but need fine tuning. https://sites.google.com/site/pjsprogra ... g/analysis - use GroupZ to enter the plots and multigroupz to enter velocities and sight settings.
Thirdly I will post some targets (There is far too many to post on here and all are similar if the rifle is in tune so one or two will suffice). For those that like the real world (ie show me on the target! - I don't believe this modelling stuff... ) .