Weight sorting cast bullets: - all that and a bag of chips?

[Bjornb]

-Sorry, I couldn't resist using a Goodsteel-ism in the thread headline.

For some time, and especially since I got involved in the XCB rifle and bullet project, I have religiously weight sorted all my bullets cast for High Velocity. The bullet I shoot the most is the NOE 31-165 (XCB), and I spend long hours building bell curves, sorting and bagging the bullets I cast. Then they are loaded in 10-shot strings with every bullet in each string weighing exactly the same down to 1/10 grain (the limit of my scale).

So I got to thinking: Is there a way to quantify the importance of this practice of weight sorting, in a way that's statistically valid? You be the judge, but here's what I came up with:

From a casting session that yielded a gross quantity of 474 bullets (linotype), I culled 29 for physical defects, for a net of 445. With the 445 bullets sitting in a plastic container, I asked my daughter to pick out 30, and to put them in a plastic bag. They were put aside and no further weighing or inspection was done with these bullets.

This left a balance of 415 bullets, which were weight sorted into this bell curve:
138403

Not a spectacular bell curve, but not totally cr@ppy either.

I then selected 30 bullets from the largest group in the curve: these weighed 154.4 grains naked.

All 60 bullets were then gas checked (Hornady), lubed (Lars 2700+), sized (.310 Buckshot push thru) and loaded in cases that were from the same batch of originally formed W-W cases. CCI 200 primers and a thrown charge of 52 grains WC867 was used. From experience this load gives me right around 2360 fps on the average, so I saw no need to hook up the MagnetoSpeed.

Shooting protocol: 2 foulers (same lube and powder) from a clean barrel, then 30 shots with 2 minutes between each shot. Every 7-8 shots the pause would be slightly longer when Cease Fire was called at the range (we shoot 15 minute volleys).
Then the barrel was cleaned (1 wet patch Ed's Red, 2 dry patches), then repeat as above.

All said the shooting took 3 1/2 hours, and I have to say the results were not what I expected:
138406

I made a double take and re-checked my ammo boxes, but the picture correctly shows what happened. I was surprised.

[sdcitizen]

What are the odds that linotype is less susceptible to forming internal voids? Your results boggle the mind!

[Hannibal]

Perhaps, to some extent, this speaks to the skills you have developed as a caster/sorter. But the question also begs to be asked, following visual inspection, at what point do weight variances become important to down range performance?

VERY interesting.

Thank you for your continued efforts. Never a dull post ! 8-)

[Pb2au]

I was wondering how long before someone did this exact test when the weight sorting topic was running hot.
It would be interesting to repeat the same test again, although 30 per batch is a nice sample size.
In industry when we run CPK testing for client machine acceptance, clients typically measure at least 50, if not 100 (thanks GE,,,,,) samples off of our machines to measure and understand accuracy and repeatability. ( I work for a manufacturer of machine tools)

thank you very much for sharing this, it is very interesting.

[Bjornb]

I was wondering how long before someone did this exact test when the weight sorting topic was running hot.
It would be interesting to repeat the same test again, although 30 per batch is a nice sample size.
In industry when we run CPK testing for client machine acceptance, clients typically measure at least 50, if not 100 (thanks GE,,,,,) samples off of our machines to measure and understand accuracy and repeatability. ( I work for a manufacturer of machine tools)

thank you very much for sharing this, it is very interesting.

I will most definitely run the exact same test again. Mainly because I didn't believe my own eyes!

[MBTcustom]

It's my personal opinion that weight sorting does very little once you achieve a certain proficiency with your casting. I think that if you were to dial in your casting till that bell curve was tighter, you would see both groups shrink, simply because you have a more controlled process. Using the weight of bullets to plot bell curves is different than weight sorting. I support using bell curves to learn to be a more consistent caster, but once you have the prescription dialed in for each mold, it really comes down to controlling things that you cannot possibly measure by observing the trends of the things you can measure.

[RogerDat]

There is just one more variable to remove that would make it double blind. You need to remove knowledge of which batch of 30 is which to remove any subtle bias that might impact your shooting.

[pworley1]

Both groups speak well of your casting and shooting skills. The main question I have is "did this experiment bring you enjoyment or frustration?". If enjoyment then it was very worthwhile, and I suggest further testing. If frustration, then I suggest you move on. Life is too short to frustrate yourself on purpose.

[Bjornb]

"There is just one more variable to remove that would make it double blind. You need to remove knowledge of which batch of 30 is which to remove any subtle bias that might impact your shooting."

True, but since I'm a one-man operation I have no way of "blind drawing" one batch or the other, and then know for sure which is which after the shoot.

[Bjornb]

Both groups speak well of your casting and shooting skills. The main question I have is "did this experiment bring you enjoyment or frustration?". If enjoyment then it was very worthwhile, and I suggest further testing. If frustration, then I suggest you move on. Life is too short to frustrate yourself on purpose.

That's a valid question. Answer: I thoroughly enjoy doing these "tests". I usually confer with Goodsteel, Larry Gibson and Sgt. Mike about what I'm planning, and they always give good advice that I take note of, and sometimes even follow!

[MUSTANG]

Scratch head over results.
Consider variables, stand back and look again.

The one way out possibility I see is the weighing and sorting was done before lube/sizing. What is the possibility that inconsistencies in the sizing/lubing operation resulted in the outcome being 180 degrees from what most of us would have forecast if asked before your results were published?

[texassako]

I tried a similar test in the fall with my favorite rifle and its favorite mold, the NOE 311331. I got similar results and just visually sort now, or occasionally put them on a digital scale to cull any outliers if I am doing something special with them. I boiled it down to experience with the mold and how it casts making the weight curve small enough that other factors play a larger roll in accuracy at the relatively short 100 yard range I shoot at. I made it double blind by having my wife number my 2 load sheets, holding them for me, and just putting the number in the box.

[scottfire1957]

One grain is one seven thousandth of a pound. That is a very very small number.

A small, small number. .00014 lbs. Teeny tiny. Lilliputian.

Add that to the fact that each and every shot travels at a different velocity, as small as that difference may be.

AND what does the one or 6 granules/flakes of powder difference dispensed for the same load make? We're talking about thousandths of a grain here. Thousandths of a thousandth of a pound.



A lot to worry about.

[Sekatoa]

Another observation...I'm not feeling doing the math tonight, but just looking at bell curve, I'd say it he odds a high percent of randomly pulled bullets are in fact the same weight as your measured group, or from the next closest on either side, are pretty good. So, your are not really comparing your control group to the full +/- spectrum of this casting session. But I understand that wasn't exactly your goal here either.

I would say in addition to the blindly pulled bullets, I would consider a batch be loaded from each end of the curve. Comparing those two groups to your other two could further illustrate the total possible spread for the casters ability.

Then, it also occurred to me that these results not only reflect casters ability, but likely the alloy, mold, rifle, etc.; meaning that the results of sorting the cast bullets may worth it more for some alloys, et al, than others?

[Cowboy_Dan]

Personally, I would have weighed the random group. Might have even rejected it if it too closely resembled the all one weight group.

[mongoose33]

I have a background in statistics; I must say I'm amazed and delighted to see these kinds of analyses being done. What's especially delightful is the search for alternative explanations of the result.

A few comments coming late to the parade:

1. If the one group was shot prior to the other group, what might have changed is atmospheric conditions, humidity, temperature, wind. Over a 3 1/2 hour time frame, that's possible. Especially wind. Should you be inclined to repeat this, a way to reduce that possibility is to alternate shots on two targets side by side.

2. If you take away the top, far right, and bottom right rounds, and compare groups, they are essentially identical. It is those three holes that enlarge the group. These could be flyers, gusts of wind, etc. I took the liberty of downloading the pic and erasing those three holes:


138412


The groups, save for those three instances, are the same to my eye. So there's not as much difference here as might appear. The vast majority of boolits from both groups performed similarly, which tells me the weight differences probably aren't meaningful.

One other thing I note is that if you look at the rounds outside the ragged hole, on the left they were random-appearing in their distribution around the hole; on the right, the errors tend toward the right. That partly makes me wonder if there were wind gusts from the left on that trial.

3. Were they shot from a sled? I'm guessing you just used a sandbag rest or similar, because undoing from a rest like a Lead Sled would have taken longer to clean and reset. That introduces shooter error--I'm not being picky here because those are pretty darned good groups, and the patience needed to do this for 3+ hours is amazing. Just noting that as, with observation number 2 just above, all it takes is three flyers to make the groups look different.

[Pb2au]

It's my personal opinion that weight sorting does very little once you achieve a certain proficiency with your casting. I think that if you were to dial in your casting till that bell curve was tighter, you would see both groups shrink, simply because you have a more controlled process. Using the weight of bullets to plot bell curves is different than weight sorting. I support using bell curves to learn to be a more consistent caster, but once you have the prescription dialed in for each mold, it really comes down to controlling things that you cannot possibly measure by observing the trends of the things you can measure.

I got that from your thread on subject. Another way to put it is that your bell curves act as the canary in mine. When the curve flattens, it indicates an shift in the repeat ability/consistency in the methodology.
Bjornb's testing now starts to shed light on a bigger picture. It would serve people quite well to subscribe and pay attention to this thread. It is quite revealing.
When we pareto information like boolit weight (IE your bell curve) it should, and in most cases does reveal that out of say a matrix 30 boolit weights against 400 boolits, we will want to see a small amount of weights accounting for the bulk of the interrogation.

Again, thanks Bjornb for posting this test. I will eagerly await the next round.

[Love Life]

Which group did you shoot first?

[JonB_in_Glencoe]

A while back, I recall someone [who's opinion I respect] saying that these small weight differences probably won't show up on the target til 200 yards or 300 yards or beyond.

[captaint]

Mongoose has a point indeed. Very interesting test just the same. Thanks for the effort.

[Bjornb]

Which group did you shoot first?

The group on the left. And, yes, there was a breeze coming from about 7-8 o'clock that may have had a small effect.

Mongoose's points are well taken. Especially his advice that the shots be taken alternatively so that wind effect, if any, is evenly distributed between the groups.

Larry Gibson made a very valid and important point in a text to me, where he pointed out that I was shooting too slow with the 14" twist to really show any difference between the two groups; that the speed and RPM (2360 and 123,500 respectively) translate to 1715 fps in a 10" twist and is a velocity where "most any quality cast bullet will shoot well". I agree completely with Larry, and I'll compile and shoot the next 2 groups using this advice and also various tips that have been given to me since I posted this. My goal for this "test" is still the same: to verify whether it makes sense to weight sort bullets for shooting HV at 100 yards (JonB, you may well have a point there).

[Dan Cash]

A very interesting test. One thing not considered was external changes in the environment that can cause groups to open. Temperature, wind, sun angle on target; all can and do influence group size. Last winter when Barabruce and I were discussing water proofing paper patched bullets I fired a test group with ammunition that has demonstrated fine accuracy from the rifle used. Only flaw was that the temperature was 7 degrees F. Groups looked more like a pattern from a modified choke shotgun. This spring, with temperatures in the low 60s, the same amm and gun went back to producing 1.5 to 2 inch groups at 100 yards. If those groups don't represent fine accuracy to you folks, keep in mind that the gun is an 1895 Winchester with an aperture sight and my eyes are 68 years old.
I would not worry about the weight sort unless you'r working on 1000 yard targets. What Goodsteel said.

[trapper9260]

I am with Dan Cash on weight of 1000 yard targets.I do not weight my unless I go for long targets otherwise i do not.Also when I do weight them I do it after I size and lube and GC them. Then I go with +-.05 of 1 gr. That is the group I go with.I did a random pick and had flyers before I weight them and then when I start to weight them, then I did not get the flyers like I did before I did not weight them.Hope this help some, but also you need to go with for all that was stated.When after I do weight them I go with the most on the heavy side.

[Love Life]

Don't forget to account for shooter fatigue.

[ascast]

wow again, a thread that is exciting to read! Lot of good comments here, I would add, 1) did you check seated bullet readout? concentricity? a few out at 3-4 thou or more would open a group that much. 2) maybe shooter fatigue? sun? 3 1/2 hours would kill me. 3) get your daughter more involved from the start and load blind - group A and group B. Never underestimate the unconscious factor. 4) once you get the blind angle nailed down, shoot a group of known bad bullets.
Are you using a scope? I have known groups to open up a lot after the first observed flyer; unconscious factor again just sayin
nice shooting and nice testing
cant wait 'till next report

[popper]

Don't forget to account for shooter fatigue. Look a lot like my 50- 100 shot events. I'm also curious as to the 'really heavy' sorted ones. I recently did a similar test on 50 random, one really heavy, mic'ing & magnified inspection showed NO difference I could detect. Question are - why really heavy? Lighter ones less 'perfect"? I also resorted one of the columns and got completely different answer, FA electronic scale.

[Litl Red 3991]

The group on the left. And, yes, there was a breeze coming from about 7-8 o'clock that may have had a small effect.

Mongoose's points are well taken. Especially his advice that the shots be taken alternatively so that wind effect, if any, is evenly distributed between the groups.

Larry Gibson made a very valid and important point in a text to me, where he pointed out that I was shooting too slow with the 14" twist to really show any difference between the two groups; that the speed and RPM (2360 and 123,500 respectively) translate to 1715 fps in a 10" twist and is a velocity where "most any quality cast bullet will shoot well". I agree completely with Larry, and I'll compile and shoot the next 2 groups using this advice and also various tips that have been given to me since I posted this. My goal for this "test" is still the same: to verify whether it makes sense to weight sort bullets for shooting HV at 100 yards (JonB, you may well have a point there).

Consider doing something a bit different with the blind sample group. The way it's done, completely blind, leaves you, well.... completely blind. There is no way of knowing what amount of deviation in weight actually signals inaccuracy. But there is a strong possibility that the bullets at either end of your weight range are the ones most probable to exhibit whatever inaccuracy weight deviation can cause. So redirect your test to see what a pile made up of 15 of the lightest and 15 of the heaviest do on paper. I would also suggest you shoot the light on one target and the heavy on another and superimpose the two targets.

BTW, there is a really simple way to do that superimposing. Use a single backer target behind another. Shoot 15 lights and pull the front as the proof target. Place a clean target over the backer as perfectly aligned as possible. Shoot the 15 heavies and you've got 3 very telling targets now. I've done a bunch of tests like that, and it's very worthwhile.

After the first time proofing a specific bullet, I quit wasting the time shooting the single weight bullet target. I wanted to see how much the weight divergence my casting would affect the accuracy and the backer and other two targets tell me what heavy will do, what light will do, and what AOIs result. And it takes less time shooting which improves the quality of the test.

Something to consider...

[Litl Red 3991]

And keep in mind that an inaccurate gun will improve your shots 50% of the time. So if you can't shoot better than the gun, half your "misses" will be improved by the gun. And you'll wind up with a chance to have far better targets every so often as well as far worse than what you actually shoot overall.

lol... sorry, but I had to mention that actual situation. It's why statistics protocols push for multiple tests and larger samples before accepting results.

[Litl Red 3991]

The best thing about having a testers mentality, is you very easily come up with reason after reason to go shoot.

Alas, the testing never seems to end..... big smile BIG smile

[bangerjim]

I read the weight of the boolit on the mold, look up the load, cast them and shoot them. Mucking this fun hobby down with all kinds of statical math takes all the fun out of it! (I deal with enough math in my company!)

Cast, size, PC, size, load, shoot......never weigh any of them! As long as there are no wrinkies or poor fills, I am good to go.

If I am after accurate shooting, I use commercial FMJ's.

Works for my meager shootist skills!

banger

[Bjornb]

Durn it Banger, I shoulda consulted you years ago! Woulda saved myself a ton of work!:kidding:

[Schrag4]

Forgive my ignorance (and I am ignorant on the subject), but wouldn't a difference in bullet weight alone result in vertical stringing alone, meaning that just the POI is shifting due to a heavier bullet going slower and a lighter bullet going faster?

If something else about what makes the bullet lighter or heavier is changing the accuracy, like the length of the bullet or how fully it filled out the mold (its "shape"), then I would expect all of some specific weight to have the best accuracy, but it might be the lightest, it might be the heaviest, or it might be somewhere in between. If that's true, perhaps the ones in the middle of your curve are just less accurate than the heaviest ones and/or the lightest ones, and your group of randomly chosen bullets had fewer of the least-accurate ones in the mix.

It seems to me that you need to cast about 10,000 of these and try all kinds of different tests. These threads are fascinating, thanks for posting!

[rintinglen]

I have a background in statistics; I must say I'm amazed and delighted to see these kinds of analyses being done. What's especially delightful is the search for alternative explanations of the result.

A few comments coming late to the parade:

1. If the one group was shot prior to the other group, what might have changed is atmospheric conditions, humidity, temperature, wind. Over a 3 1/2 hour time frame, that's possible. Especially wind. Should you be inclined to repeat this, a way to reduce that possibility is to alternate shots on two targets side by side.

2. If you take away the top, far right, and bottom right rounds, and compare groups, they are essentially identical. It is those three holes that enlarge the group. These could be flyers, gusts of wind, etc. I took the liberty of downloading the pic and erasing those three holes:


138412


The groups, save for those three instances, are the same to my eye. So there's not as much difference here as might appear. The vast majority of boolits from both groups performed similarly, which tells me the weight differences probably aren't meaningful.

One other thing I note is that if you look at the rounds outside the ragged hole, on the left they were random-appearing in their distribution around the hole; on the right, the errors tend toward the right. That partly makes me wonder if there were wind gusts from the left on that trial.

3. Were they shot from a sled? I'm guessing you just used a sandbag rest or similar, because undoing from a rest like a Lead Sled would have taken longer to clean and reset. That introduces shooter error--I'm not being picky here because those are pretty darned good groups, and the patience needed to do this for 3+ hours is amazing. Just noting that as, with observation number 2 just above, all it takes is three flyers to make the groups look different.

One of my pet peeves with the use of statistics is to "prove" or "disprove" assertions by altering the facts. The fact is that the non-sorted 30 shot group does not have 10% fliers that serve to increase the group size by nearly 50 percent. Arbitrarily eliminating those "fliers" does nothing to change the facts. Photoshopping a picture of Scarlett Johannsen onto my wife's photo does not alter the underlying reality that there are considerable physical differences.

What is interesting and requires further examination is the cause of this disparity. Is it real? Or was there a change in shooting conditions that caused some boolits to drift afield? I eagerly await further results.

[MBTcustom]

Photoshopping a picture of Scarlett Johannsen onto my wife's photo does not alter the underlying reality that there are considerable physical differences.

What is interesting and requires further examination is the cause of this disparity. Is it real? Or was there a change in shooting conditions that caused some boolits to drift afield? I eagerly await further results.

Gosh that made me laugh! So true!!!

Still, the fact that the "larger" group was caused by the bullets that were weight sorted really tells the tale, regaurdless of the three fliers. It's safe to say that the three fliers were caused by something other than the weight disparities between the two groups.

The point that I find most compelling is that these groups were shot niether at high velocity, nor at long range. There very well may be an observable differance if Bjorn turns up the heat on either of these scenarios.

The fact that the less controlled bullets shot better leads me to believe that the two groups are in fact identical and the three fliers were caused by condition changes/shooter fatigue/ light changes etc etc etc.
In the future, alternating shots between the two targets may very well spread the error more evenly between the two targets, but regardless, we can't forget the objective here and do a sanity check once in a while. We want to take note of solid data, not fluke incedences.
I for one am very glad that the test went the way it did, and it really begs the question: had the fliers gone the other way, would we now be singing the praises of weight sorting, which would in fact be in error in this instance? That's a scary thought.
Definitely something to keep in mind in the future, and gaurd against.

[jhalcott]

At one silly wet shoot a man said "IF you THINK it helps , IT DOES"! I tried this same test years ago. My son loaded the same recipe in cases with "good" and "bad" bullets. We shot them at the range and MY groups with "bad" bullets was a bit larger than the "good" ones. A second series was shot with the opposite results. I KNEW the "good" bullets shot better, but the 2nd series I was not sure which bullets were being shot. I think ,and my son agreed, that I seemed to take more care when shooting what I thought were the "good" loads.

[Litl Red 3991]

One of my pet peeves with the use of statistics is to "prove" or "disprove" assertions by altering the facts. The fact is that the non-sorted 30 shot group does not have 10% fliers that serve to increase the group size by nearly 50 percent.

Actually your fact isn't a fact but your opinion. You're guessing there aren't fliers in that group without having anything at all to base that on other than possibly visions of Scarlett dancing in your mind. No lie, there could be fliers that went toward 3 o'clock when the rifleman pulled the shot toward 9. What is a fact about those randomly chosen bullets is they could be any distribution of weights at all. Oh yeah, and there are no facts proven by their distribution since they are almost complete unknowns.


What is interesting and requires further examination is the cause of this disparity. Is it real? Or was there a change in shooting conditions that caused some boolits to drift afield? I eagerly await further results.

In fact, it's unknown if there is a disparity. Run enough samples and statistics will slowly build a case for us.

[gwpercle]

100 yards and randomly picked works for me. I tried weighing and sorting boolits when I got a new 5-0-5 scale...had to do something with that new scale....But could see no difference in shooting results . It was a lot of work sorting and segregating them into lots.
Newness wore off of the scale and no big accuracy improvement were realized, so I give up weighing and sorting.
Glad to see my thoughts about it being a lot of work for no great improvement were not do to my ignorance . Sometimes ignorance is bliss.
Gary

[mongoose33]

One of my pet peeves with the use of statistics is to "prove" or "disprove" assertions by altering the facts. The fact is that the non-sorted 30 shot group does not have 10% fliers that serve to increase the group size by nearly 50 percent. Arbitrarily eliminating those "fliers" does nothing to change the facts. Photoshopping a picture of Scarlett Johannsen onto my wife's photo does not alter the underlying reality that there are considerable physical differences.

What is interesting and requires further examination is the cause of this disparity. Is it real? Or was there a change in shooting conditions that caused some boolits to drift afield? I eagerly await further results.

I proved nothing by altering the facts. I changed the picture to illustrate just how badly our perceptions can be fooled by just a few outliers. In this case, three shots cause people to "see" a huge difference in the groups when in fact there is little. Take those three shots away and what do you have? Not much.

Further, and this is I think very clear, since the groups were shot one after the other, changes in conditions could cause the results. That said, take away the three outliers and you have very similar groups. Can't see how it could be clearer.

I tried to illustrate that concept in my post. In my decades of both teaching and using statistics and finding patterns or not in data, one thing that jumped out is how easily one's eye can be fooled by data.

Fooled enough, I suppose, to make a Scarlett Johannsen joke.

[John Boy]

Then they are loaded in 10-shot strings with every bullet in each string weighing exactly the same down to 1/10 grain (the limit of my scale).Your wasting your time sorting bell curves to 1/10gr variance!
One grain variance for shooting out to 500yds. Half grain variance 600 to 1000yds

[MBTcustom]

Your wasting your time sorting bell curves to 1/10gr variance!
One grain variance for shooting out to 500yds. Half grain variance 600 to 1000yds
That sounds like advice geared perfectly towards 45 caliber projectiles at low speed, but I suppose I agree with the spirit of your statement.

[Bjornb]

Your wasting your time sorting bell curves to 1/10gr variance!
One grain variance for shooting out to 500yds. Half grain variance 600 to 1000yds

John Boy,
You may very well be correct. However, since I started shooting cast rifle I have seen and heard enough opinions to cover a football field, and that's the reason for checking everything out for myself. And because I truly enjoy conversing with the fine group of people that frequent Cast Boolits, I put it up there for everyone to see if they should be so inclined.

I'm sure that a good many shooters agree with you, and quite frankly I wouldn't mind agreeing with you myself (would save me hours of work). So when I'm done re-shooting this little test with some refinement, I will hopefully know for sure if your above statement is indeed correct.

[Litl Red 3991]

John Boy,
You may very well be correct. However, since I started shooting cast rifle I have seen and heard enough opinions to cover a football field, and that's the reason for checking everything out for myself. And because I truly enjoy conversing with the fine group of people that frequent Cast Boolits, I put it up there for everyone to see if they should be so inclined.

I'm sure that a good many shooters agree with you, and quite frankly I wouldn't mind agreeing with you myself (would save me hours of work). So when I'm done re-shooting this little test with some refinement, I will hopefully know for sure if your above statement is indeed correct.

Lots of people think they'll know for sure after one good test. Good thing for most people who really enjoy shooting, is one test is nowhere close to enough. But it might suggest a better, shorter way to test.

You want to know what effect weight variation has. Test weight variation. Shoot some of your lightest and some of your heaviest. Alternate shots from the two piles if you're really worried about changing conditions, otherwise depend on your judgement of conditions and evaluate their effects.

There are excellent reasons that the science of statistics requires sufficient samples for reliability. And better reasons for them to explain that they aren't providing proof, just information and it's probable value.

Right now, none of us have any idea how accurate your rifle really is. For anyone to get "the truth" out of 2 groups isn't really possible. But it's a start in the right direction.

[MBTcustom]

Right now, none of us have any idea how accurate your rifle really is. For anyone to get "the truth" out of 2 groups isn't really possible. But it's a start in the right direction.

Not true. I know exactly how accurate Bjorns rifle is. I built it.
I have TIR numbers for every critical dimention on that rifle from the crown to the cocking piece. The rifle is capable of less than 1/2MOA, as are the other XCB rifles.
Sorry buddy, that's an MBT rifle and MBT rifles are known entities:
This was shot with the original vintage barrel. The new barrel the rifle is using now is even more accurate.
138483

Actually, I know what you meant, but I couldn't resist the opportunity to take a Viking spear to one of your bubbles of negativity.
:kidding:

[Litl Red 3991]

Do you feel that "capable of" describes the accuracy?

Those two targets from the original post suggest the rifle didn't do 1/2 minute with either pile of test bullets. That would suggest there is some other more dominant reason than weight variance affecting that tack driver.

Sorry to have boiled your Viking blood but one test that failed to include any recorded measure of weight variance really won't prove what effect weight variance had on the outcome. I figured BOTH targets from the original post showed how accurate the rifle can be. Just as validly as any single "capable of" target does.

[MBTcustom]

Do you feel that "capable of" describes the accuracy?

Those two targets from the original post suggest the rifle didn't do 1/2 minute with either pile of test bullets. That would suggest there is some other more dominant reason than weight variance affecting that tack driver.

Sorry to have boiled your Viking blood but one test that failed to include any recorded measure of weight variance really won't prove what effect weight variance had on the outcome. I figured BOTH targets from the original post showed how accurate the rifle can be. Just as validly as any single "capable of" target does.


You didn't boil my blood, and I'm Scottish not Viking (that's Bjorn).
I was only jesting and I knew exactly what you meant. From a purely statistical point of view, you're right as rain.

[Litl Red 3991]

You didn't boil my blood, and I'm Scottish not Viking (that's Bjorn).
I was only jesting and I knew exactly what you meant. From a purely statistical point of view, you're right as rain.

And I'm sorry to have probably put a spin on this thread. It's always fun to dig into a topic like this. But years of trying to help guys shoot (and reload) better are to blame. Every target tells us something, but what that is..... isn't usually everything we seem to think.

[Bjornb]

My friend, there's no boiling blood here. Some of the advice given since I started this thread is very good and will be followed next time I try a comparison shoot. Some of the advice doesn't really speak to what I'm trying to do, but that doesn't make it bad advice.

My goal was to determine whether weight sorting made a difference on the target when shooting cast bullets at high velocity. I'll regroup (reload) and try again, and only the targets will show if I made any progress. Stay tuned.

[MBTcustom]

And I'm sorry to have probably put a spin on this thread. It's always fun to dig into a topic like this. But years of trying to help guys shoot (and reload) better are to blame. Every target tells us something, but what that is..... isn't usually everything we seem to think.

I don't see it that way at all. I think your comments were very pertinent to the discussion at hand.

[GrayTech]

Instead of 30 randomly selected as a control, select 3 or so from each stack in the bell curve. That way you KNOW you have a spread that will be shot in random order.
Having said that, I tend to agree that a longer range will amplify any variance.

[Litl Red 3991]

138603

Funny thing that this example popped up (or out) when discussing weight rejects. What the picture shows is lube "decompressing" out of a just-sized and lubed bullet. The bullet was in a reject pile that was going to the range tomorrow to see what effect comes from rejects in a new rifle.

Every time I get a new mold or a new gun, one of the first tests is to see how weight rejects shoot from that mold or from that gun. I just got a new 40-70 Sharps Straight rifle. Matter of fact, it came yesterday. Best thing is I now have a bunch of reasons I got to go shoot. Heck, the list probably will cover a couple of months of shooti.... uh.... testing.

The bullet pictured was obviously from the light pile. For once, the reason for the light weight is clear. This time, the mystical, never seen but often talked about interior void made itself obvious. The sizing/lubing filled the void under pressure and the lube started depressurizing while the sizing was going on.

[Litl Red 3991]

The reason every new mold AND every new gun gets tested with weight rejects is because their impact (pun intended) isn't always a given. Stability, or in our case instability, isn't just a bullet thing. Instability can come from normally stable bullets being fired in guns that have problems of their own to share with the bullets.

I've got a couple of Dan Wesson 32mags that have a big history of punching slightly oblong holes in paper. They didn't do it back when they were new. Now they do a lot. How is that? Why is that?

I got them to shoot silhouette. The cartridge isn't the greatest ram killer in silhouette. Those steel knockovers out at 100 won't reliably fall just from 115grains of lead. The lead has to be honking, or at least not loafing. Stability comes from bullet length being spun adequately. Adequate spin comes from velocity applied to barrel twist.

In the last couple of months the DWs have been providing some fun in an indoor league here in town. During the first week of the league I noticed the chosen pistol seemed to have lost it's accuracy. So the second week, the other pistol got a turn. It wasn't much better. So I figured SOME TESTING WAS REQUIRED!!! Turns out I was shooting a new bullet in those pistols. Turns out I hadn't done a reject load test. Turns out that the 90 grain bullets (that should have flown more stable because they were shorter) were flying so much slower they were showing tipping on the paper, and punching groups about the size of a 9 ring. Truth is, it was a surprise because just slowing down bullets doesn't usually cause the problem. Shooting longer ones is the usual cause. What provided the extra problem was those DWs.

They weren't exactly the best mfg'd pistols ever, and that's why DW went bust. And weren't around very long when they were around. I'm guessing they chose the twist rate they did for the 32s because they were starry eyed over the "magnum" name on the cartridge. Unfortunately, even the cartridge wasn't worthy of the name. And DW didn't make great decisions from top to bottom. One pistol had a shroud that fit the frame about a degree or two off in windage. That plays hell with your mind when trying to figure out why sight settings are weird and way off. Also, an extra barrel I got for them didn't happen to have any forcing cone reamed in it. It did have what looked like two turns tapped into it for a big screw (about 32caliber to be exact) however. No lie. I really wish I'd seen that back when DW was still operating. The repaired barrel gets tested soon as it was just now fixed.

The pistols used to shoot "weight reject" cast bullets without problems. And then had problems shooting them. There is more to the issue than meets the eye.

[MBTcustom]

Litl Red, it looks to me like your bullet is literally "pooped out".

[Litl Red 3991]

Litl Red, it looks to me like your bullet is literally "pooped out".

Every time my bullets poop out, I just go make some more. It's a perfectly self-sustaining hobby for sure.

Replacing poop with pop is never ending. Thank goodness...

[HangFireW8]

A few things.

First, not all median boolets are there for the same reason. Some may be fat with a void. Some may be thin but more dense.

Second, statistically speaking, your groups are not that far apart.

Try shooting two groups, alternating ammo and targets, Left/A then Right B then repeat. This helps even out environmental variables.

[rking22]

First , thanks for doing all the work and posting results to trigger this discussion! Just for kicks and giggles what about 6 , 5 shot groups of each type, shot alternately and as "blind" as possiable.Let your daughter color code your loads and mark you groups for you. You will not know which is which, only she knows that untill your done shooting ,and measuring.Also intentionally select 30 bullets across the full weight distribution. Then the group to group variation between the "control" bullets groups can be compared to the same on the "test" bullets. More data samples with the same shooting and more equal sharing of other variables. With those 12 groups other measurments can be done as the data comes together and suggest more directed tests with more control of variables.
I too, doubt there is a "signifigant" difference bettween the 2 groups. Not enough data and too many uncontrolled variables to make a judgement, other than the weight variance is not the Red-X in this "problem".
I used to weigh every powder charge until I did this type test on a 308Win. All my match ammo except 600 yd prone got thrown charges after the test. There were more prevelent variables at work than just the powder charge, just like here.
Also, I do not expect the .1 weight distribution to show any difference until things are "accelerated", more FPS and/or more distance will "seperate" the data. But then, I put little to no stock in SD of velocity readings as long as they are somewhat reasonable. Low SD can predict a forgiving load, but there are way more important variables at work in most loads. I kept track of published load tests from Handloader Magazine once, over a year there was less than 10% of the published loads that had both the best group and the lowest SD. From that "data" one could conclude that low SD is a predictor of poor accuracy performance. Not true, but it did show that there are other variables that have a larger contribution to average rifle preformance. Can't be too quick to jump to conclusions!