Any explanations?

[boisepaw]

This is a follow-up to an earlier thread of mine. Remington 700 rifle…reloading 185 grain Berger Juggernaut with Varget and H4895, Lapua brass, CCI primers. Shooting at 100 yards off bench, bipod and bags.

The first photo is 42.9 grains of H4895. SIX rounds in 7/16 of an inch. Ave 2624 FPS, SD = 18, ES = 48

The second photo is 44.4 grains of Varget. Five rounds in 1.5 inches. Ave speed 2579 FPS, SD = 7, ES = 20.

With 41.7 grains of H4895 I had another six shot group at ¾ inch but an SD of 13 and ES of 34.

Why the heck is such a GREAT group coming from such lousy SD and ES? And vice versa, such a modest group from a very nice SD and ES?

What gives?

 

[NBPRP]

By chance did you get the two targets turned around so actually the good group was shot with the good load and the crappy target was shot with the crappy load?

Or did you shoot the good target first and after taking a look at it pounded down a double expresso so you were all jitted out when you shot the second target. Hence you were all over the place?

Just asking.

 

[hafejd30]

It’s not uncommon to see the best groups not always show the best velocity consistency. I let my target tell me what my gun likes

 

[NBPRP]

Then again I remember something in one of the shooting manuals you could buy at Camp Perry that had articles/discussions from the likes of Gary Anderson, Greighton Audette, Carl Bernosky, etc. that address an interesting phenomenon in which barrel harmonics plays a part in accuracy. There was talk about an image of a water hose and how it recoils somewhat when you turn the water on until the slug of water exits the end of the hose.

In a similiar way they said on a much smaller scale the barrel acts like the hose and the bullet is like the slug of water. There were even some graphs that showed the different between faster vs. slower bullets and whether they were exiting the barrel on the up swing or down swing and how that would effect point of impact.

If I ever find that manual I will have to double check to make sure I am not just blowing smoke.

 

[MarkyMark007]

at short range ES/SD is not corelated with group. at long range, there is no good group with bad ES/SD.

and this is not an explanation, you just don't know what is ES/SD.

 

[straightshooter1]

View attachment 7890552View attachment 7890553
This is a follow-up to an earlier thread of mine. Remington 700 rifle…reloading 185 grain Berger Juggernaut with Varget and H4895, Lapua brass, CCI primers. Shooting at 100 yards off bench, bipod and bags.

The first photo is 42.9 grains of H4895. SIX rounds in 7/16 of an inch. Ave 2624 FPS, SD = 18, ES = 48

The second photo is 44.4 grains of Varget. Five rounds in 1.5 inches. Ave speed 2579 FPS, SD = 7, ES = 20.

With 41.7 grains of H4895 I had another six shot group at ¾ inch but an SD of 13 and ES of 34.

Why the heck is such a GREAT group coming from such lousy SD and ES? And vice versa, such a modest group from a very nice SD and ES?

What gives?

The vertical in the second pic looks pretty good to me; it's the horizontal that suggests to me it's more about something going on the the shooter's mechanics.

 

[Govt Mule]

What MarkyMark said. Stretch it out to 300 plus yards and see what the loads do. SD and ES are not the end all for choosing a load.

 

[iceng]

Ill echo everyone here. ES SD so not make tight groups. Yes they often occur, but not as a direct result.

Often the best shooting load dont have the best ES SD, but again, it does occur.

 

[Oryx]

Just something to keep in mind that many people often gloss over. ES/ED are statistical terms and in statistics "group size" would typically refer to the number of items you are measuring in your sample. A sample of 3 or 5 velocities really isn't providing enough data to reliably predict outcomes.

That said, the velocities are only one of the many known variables for measured accuracy. As mentioned earlier, the velocity is likely not to blame for the difference in the two groups.

 

[boisepaw]

By chance did you get the two targets turned around so actually the good group was shot with the good load and the crappy target was shot with the crappy load?

Or did you shoot the good target first and after taking a look at it pounded down a double expresso so you were all jitted out when you shot the second target. Hence you were all over the place?

Just asking.

Normally I would say either of those are good possibilities but…nope.

 

[boisepaw]

It’s not uncommon to see the best groups not always show the best velocity consistency. I let my target tell me what my gun likes

My question/problem is that when I want to go out to greater distances…1000 yards or so…I’m told that SD and ES are critical measurements.

 

[boisepaw]

at short range ES/SD is not corelated with group. at long range, there is no good group with bad ES/SD.

and this is not an explanation, you just don't know what is ES/SD.

See my response above to hafejd30. I do understand the concept. That’s the reason I reload. But that being the case, wouldnt that suggest that the load with the nice low SD and ES will shoot tight groups at distance?

 

[rmfield]

Simply too little data. You'll have to shoot a few more groups with each to get the explanation you are seeking..

 

[AccuSol-ERN]

In my experience and quite a bit of research.......it has to do with barrel whip and the specific point of bullet release in the wave.

I bet if you put a tuner on and shot that lateral group again while dialing in the tune......it would be great and hold true at distance as well.

You can also do the above with bullet seating depth.

Ern

 

[Dstoenner]

at short range ES/SD is not corelated with group. at long range, there is no good group with bad ES/SD.

and this is not an explanation, you just don't know what is ES/SD.

I disagree with that statement. That says that somehow at distance a bad group at 100 converges at distance. That doesn't happen. The dispersal continues at distance. A bad group at 100 is a bad group at 300 or 1000.

I have run into this issue myself and have come to the following conclusions about what is going on.

1) SD/ES are a function of internal ballistics which is a function of primer, powder, case volume, bullet dimensions and drag coefficent of the bullet material and seating deepth.

2) When the primer is hit the contained explosion creates a mechanical impulse to the barrel sending shock waves to the muzzle which then oscillate back and forth. If the bullet exits at a node where the muzzle is not moving much you get good tight groups if the SD and ES are not the best.

The H4895 load mirrors #2 while the Varget mirrors #1 and doesn't exit at a mechanical node.

Notice that 2 different powders had 2 different results. Now I know you are after the highest velocity with a nice low single digit SD. You just might not get there from where you are. You need to change one variable at a time. I would recommend seating depth first. And you need to do spread of charges. I do a spread of 2 gn's, 10 charges at .2gn steps. I load 4 at each charge. When I go to the range I shoot the 4th of every .2 step checking the primer for signs of high pressure or hard bolt lift. That also fouls the barrel to get a good indication when I shot the groups of 3 recording the velocity and statistics for each group. This then gives you a good idea where you nodes are and how ES/SD are matching up to the nodes.

Sorry to be the bearer of bad news. But I know you'll find a solution. I went through this with my first 260. I went through 800 rounds trying different things. I was talking to a gunsmith and competitor about my woes and he said 42.0 gns of any 4350 powder always shoots well. My final load turned out to be 42.5 gns of H4350 ina 30 inch barrel. That worked for 2 barrels from different manufacturers. Go figure.

Let us know how it works out.

David

 

[boisepaw]

In my experience and quite a bit of research.......it has to do with barrel whip and the specific point of bullet release in the wave.

I bet if you put a tuner on and shot that lateral group again while dialing in the tune......it would be great and hold true at distance as well.

You can also do the above with bullet seating depth.

Ern

That is a very interesting observation that I hadn't thought of. I was going to work on seating depth next...once I found a group with BOTH small size and good ES and SD. Which of those factors are most positively affected by playing with the seating depth?

 

[boisepaw]

I disagree with that statement. That says that somehow at distance a bad group at 100 converges at distance. That doesn't happen. The dispersal continues at distance. A bad group at 100 is a bad group at 300 or 1000.

I have run into this issue myself and have come to the following conclusions about what is going on.

1) SD/ES are a function of internal ballistics which is a function of primer, powder, case volume and bullet dimensions and drag coefficent of the bullet material.

2) When the primer is hit the contained explosion creates a mechanical impulse to the barrel sending shock waves to the muzzle which then oscillate back and forth. If the bullet exits at a node where the muzzle is not moving much you get good tight groups if the SD and ES are not the best.

The H4895 load mirrors #2 while the Varget mirrors #1 and doesn't exit at a mechanical node.

Notice that 2 different powders had 2 different results. Now I know you are after the highest velocity with a nice low single digit SD. You just might not get there from where you are. You need to change one variable at a time. And you need to do spread of charges. I do a spread of 2 gn's, 10 charges at .2gn steps. I load 4 at each charge. When I go to the range I shoot the 4th of every .2 step checking the primer for signs of high pressure or hard bolt lift. That also fouls the barrel to get a good indication when I shot the groups of 3 recording the velocity and statistics for each group. This then gives you a good idea where you nodes are and how ES/SD are matching up to the nodes.

Sorry to be the bearer of bad news. But I know you'll find a solution. I went through this with my first 260. I went through 800 rounds trying different things. I was talking to a gunsmith and competitor about my woes and he said 42.0 gns of any 4350 powder always shoots well. My final load turned out to be 42.5 gns of H4350 ina 30 inch barrel. That worked for 2 barrels from different manufacturers. Go figure.

Let us know how it works out.

David

Thanks so much for your careful and thorough thoughts there.

Here's a bit more info. I started, a week ago, with 11 different powder weights in .2 grain increments for each powder. I can clearly see how four rounds at each increment would give much more/better data. But I was only doing 1 at each increment.

With the Varget (the powder that yielded the large 1.5" group but the low SD (7) and ES (20)...I found that with the 11 DIFFERENT charge weights from 43 to 45 grains...that entire 11 shot group measured 1.25 inches. That's LESS than the group size of five rounds of Varget all loaded at 44.4 grains. Very confusing.

On a different note...while the rifle I'm discussing here is a 308, I found something similar to what you found above with my 6.5 Creedmoor. With that caliber I have found at least five different bullets that all shoot GREAT when loaded with 42 grains of H4350 (give or take no more than .1 grain) and all at very simliar seating depths. That caliber seems to me to be incredibly forgiving AND accurate with that particular powder.

 

[hafejd30]

What type of crono are you running?

Typically when I’m finding a load for long range I test at 300 yards initially. Then when I pick a load and test seating depth I’ll move to 500, 600 or 800 yards and group there. Not only looking for good group size but paying attention to the vertical size of the group

Many test at just 100 as it takes the wind variable and what not out of the equation. I just prefer to test at longer ranges as that’s what I’ll be shooting anyways. Easier for me to see how good the group is vertically printing on target the further I go out

Below is a few examples of what I’m looking for at those distances

284 Fclass rifle- 5 shot 500 yards

338 LM- Cold/Clean shot circled- 3 shot group after - 800 yards

260 Rem- 600 Yard- 5 shots

308- 2 rounds circled are to get initial data from StrelokPro. Then corrected. Fired 5 more rounds which are circled on top. Again checking vertical spread in the group - (440 or 475 yards. Don’t remember which). Wind did play a factor horizontally in the group but at this point I wasn’t necessarily concerned about that as I’ve already tested this load in good conditions

 

[918v]

View attachment 7890552View attachment 7890553
This is a follow-up to an earlier thread of mine. Remington 700 rifle…reloading 185 grain Berger Juggernaut with Varget and H4895, Lapua brass, CCI primers. Shooting at 100 yards off bench, bipod and bags.

The first photo is 42.9 grains of H4895. SIX rounds in 7/16 of an inch. Ave 2624 FPS, SD = 18, ES = 48

The second photo is 44.4 grains of Varget. Five rounds in 1.5 inches. Ave speed 2579 FPS, SD = 7, ES = 20.

With 41.7 grains of H4895 I had another six shot group at ¾ inch but an SD of 13 and ES of 34.

Why the heck is such a GREAT group coming from such lousy SD and ES? And vice versa, such a modest group from a very nice SD and ES?

What gives?

You put too much powder in the case.

 

[MarkyMark007]

That is a very interesting observation that I hadn't thought of. I was going to work on seating depth next...once I found a group with BOTH small size and good ES and SD. Which of those factors are most positively affected by playing with the seating depth?

bryan litz is loading: 1,5 or 2 gr from the max charge, and than he do seating test for the smallest group. this is all the magic.
and he gets small ES/SD, because this is a function of good components and very precise powder charge. but the group is a function of the seating depth.

 

[MarkyMark007]

I disagree with that statement. That says that somehow at distance a bad group at 100 converges at distance. That doesn't happen. The dispersal continues at distance. A bad group at 100 is a bad group at 300 or 1000.

Not necessarily.
Everybody is trying to shoot 1/3 MOA groups at 100y. But is this the group at 1000y also? I don't believe.
1 MOA group at 1000y will give you at F-Class a perfect score. Is this a bad group? But what about at 100y to have 1 MOA group? Not good.

This is because group size growth in not linear with distance, because speed and ballistic coeificient inconsistences give exponential growth of the group at longer distance. I see this all the time: very good group at short distance, and like a shot gun at LR...

But if you can manage to get very good velocity and B.C. spread, your groups can grow almost linear at distance.
But most people does not control this, so they need perfect group at 100y to have decent group at 1000y. Because they dont have parameters, which infect balistic, under control.
Imho...

 

[acudaowner]

I have several one you were awake for the tight group but fell asleep for the other ?
you tried shooting and did everything right on the tight group . the all over the place group you messed up and just pulled the trigger haphazardly
with your eyes closed .

my favorite The evil , racist , bigoted , homophobic , puppy killing , children hating / wife abusing , white man was holding you down on the not good group , he tired of whipping you granted you your freedom and being all excited and happy you shot a good group

you shot a really nice group , then blew the other try again or take a break then try again not that my guess is the only possible explanation cause it's not it's just my guess I have seen people loose there minds over a bad group but have only ever seen one person pull off municipal one hole 5 shot groups and even he could not do it at will it happened or it did not . Only you keep you from succeeding at anything you do .

 

[Feniks Technologies]

So, it’s already been covered as far as group size not being tied to velocity (until distance is great enough that it does).

However, I’m just going to point out what you think are really good chrono numbers may or may not be that good.

Your 5 shot 7sd group does *not* mean your actual sd for that load is 7.

What it means is your *sample* sd is 7. But a sample sd has to be extrapolated. Without going into all the details, a 5 shot 7sd means your sd will fall somewhere in between:

4 and 20fps. Using a 95% confidence interval.

So, as you can see, that 7sd is all of a sudden very questionable. And it could just as likely be as bad as the first group you shot, or that first group could actually have a better sd in the long run.

That also means your ES 95% of the time could be as low as 16fps and as high as 80fps.

 

[MarkyMark007]

https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2020/12/Chorongraph-Accuracy-and-Precision-from-Bryan-Litz-Modern-Avancements-In-Long-Range-Shooting.jpg

 

[boisepaw]

https://2poqx8tjzgi65olp24je4x4n-wpengine.netdna-ssl.com/wp-content/uploads/2020/12/Chorongraph-Accuracy-and-Precision-from-Bryan-Litz-Modern-Avancements-In-Long-Range-Shooting.jpg

I’m not sure how to interpret that graphic. Is it telling me a Magnetospeed is going to have a lower error rate than other chronographs?

 

[Govt Mule]

Another consideration is the bullet being used. 100-200 bench rest shooters in most cases are using flat base bullets, where long distance br, fclass, elr shooters are using boattails with certain angles to the boattail. Yaw and pitch of a bullet have to be taken into consideration as well.

In most cases, a one-hole group @ 100 yards will be accurate at 1000 yards, but seating depth and powder charges need to be checked at distances you will be shooting (doing a ladder test) to verify your accuracy nodes). Vertical at distance is your reloading skills controlled through neck tension and powder charges that you fine tune to the harmonics of the barrel. If the stars align, you should have low SD/ES, and targets that you can be proud of.

 

[Dstoenner]

bryan litz is loading: 1,5 or 2 gr from the max charge, and than he do seating test for the smallest group. this is all the magic.
and he gets small ES/SD, because this is a function of good components and very precise powder charge. but the group is a function of the seating depth.

I agree with that to a point. For sure it would give you more accurate numbers. But then how do you explain when doing a ladder that some are higher along the way? I believe there are resonances nodes in the the case before the bullet leaves the neck that modulate the SD/ES.

David

 

[MarkyMark007]

I’m not sure how to interpret that graphic. Is it telling me a Magnetospeed is going to have a lower error rate than other chronographs?

this picture is showing you that some chronographs are better and some are worse. and you must account for that.

 

[MarkyMark007]

I agree with that to a point. For sure it would give you more accurate numbers. But then how do you explain when doing a ladder that some are higher along the way? I believe there are resonances nodes in the the case before the bullet leaves the neck that modulate the SD/ES.

David

Fenix will tell you that ladder is most of all a too small sample of the test and a variation of the groups and inconsistent ballistic...

But I agree that you can shrink your group with powder charge also; not only with seating depth.
Because there are some known velicities for some bullets, which works the best, and everybody is loading for those velocities. This is known for F-Class, benchrest 6PPC...

 

[Doom]

Fenixs has the correct explanations. I would put it in a little different way. The target at 100yds will not indicate significant differences in velocity. A 308 168gr bullet with an ES of 100fps will only have a POI variation of ~.2”. It will indicate that the bullets leave the muzzle along a consistent path. This is the premis on which Audette and Newberry based their techniques. Audette uses a greater distance to magnify the variations. In Newberry’s system two or three consecutive loads group to the same POI, you have a good load where velocity differences have minimal effect on the trajectory of the bullets as ithey leave the barrel. As for ES and SD those parameters are much more a function of components and technique than anything else. Those parameters cannot be determined accurately from 3 or 5 shots.

Also, on a side not, picking a charge and varying seating depth versus picking a seating depth and varying powder charge are really no different. If a node exists at 43gr and 2.810”, then picking either one and varying the other must come to the same result.

 

[cas6969]

I read the title, look at the pictures and thought… “Was I shooting?”

 

[MarkyMark007]

Also, on a side not, picking a charge and varying seating depth versus picking a seating depth and varying powder charge are really no different. If a node exists at 43gr and 2.810”, then picking either one and varying the other must come to the same result.

Most of people will tell you that this is wrong. But if you pick 'known good seating depth' (where everybody has good results with this particular bullet), this is another story.
So picking your charge and work on seating depth is told to be a better way.

 

[Feniks Technologies]

Most of people will tell you that this is wrong. But if you pick 'known good seating depth' (where everybody has good results with this particular bullet), this is another story.
So picking your charge and work on seating depth is told to be a better way.

That’s not true.

There have been no definite data sets that show doing one before the other is better.

You’ll find it’s 50/50 on which people do first.

In fact, Berger (who Litz is the Chief Ballistician for) recommends using the *minimum* listed charge weight for all seating depth tests.

See the attached screenshot.

 

[Feniks Technologies]

As far as ladder testing and such…..

I can’t say it doesn’t work.

But, it’s definitely at the mercy of long term dispersion just like any other group or chronograph data.

You really need to know the ins and outs of dispersion and what your rifle may or may not be doing.

I’d be shocked if more than 5-10% of shooters can actually use a ladder test well enough to exploit the results. Let alone trust them.

 

[MarkyMark007]

In fact, Berger (who Litz is the Chief Ballistician for) recommends using the *minimum* listed charge weight for all seating depth tests.

In one interview Brian said, that he load -1,5gr or -2gr from maximum charge (just for safety reasons), and than he do seating depth test for best group. And this is how he load for matches.

 

[Feniks Technologies]

In one interview Brian said, that he load -1,5gr or -2gr from maximum charge (just for safety reasons), and than he do seating depth test for best group. And this is how he load for matches.

That doesn’t mean it’s the only way.

 

[Haney]

I’d be shocked if more than 5-10% of shooters can actually use a ladder test well enough to exploit the results. Let alone trust them.

Explain it there wise one . Let us see exactly how you do it . No links, no copy/paste and no bullshit .

 

[Feniks Technologies]

Explain it there wise one . Let us see exactly how you do it . No links, no copy/paste and no bullshit .

I don’t use ladder tests. As mentioned above, they are too subject to long term dispersion and I prefer more a more modern and IMO reliable approach.

You can go back through my posts on standard deviation and confidence intervals and pretty well surmise how I perform load development.

I doubt you’ll find anyone else saying much about that for me to copy/paste from.

 

[Ledzep]

Explain it there wise one . Let us see exactly how you do it . No links, no copy/paste and no bullshit .

Prove that small sample tests are viable and can be accurately interpreted, then.