Pellet Rolling ~~ Part 2

[Guest]

Cornpone..



Try using a thick piece of glass to roll on

the wood grain will hamper the pellet rolling. Also be careful as to how fast they roll, they'll "skid" out and skew the test. I got decent results by having the "rolling table" be raised about 3/8-5/8 inch

Dan and @darksky both of you suggested the test roller might be improved. I have seen a lot of anecdotal references by people which argue that point. Frankly I don't think it will make much difference BUT you both came to the table with something I should have considered and while I was out walking the dogs earlier it occurred to me that you might be right. I don't think you are BUT feelings don't collect data, do they? So I came back and found an old window pane. I am going to redesign the roller and run the test again.

I am going to reduce the size of the cells in the catch box to as small as practical so that I get more differentiation. Then I will run that batch and present that data either here or in another thread. That will put to bed the idea that the test bed did not discriminate sufficiently.

So ... I guess this horse is pretty battered and bruised but it might have one more race left in it. Let's see how that goes.

 

[Beginner]

Pellet sorting is what competitors attempt to do with mediocre pellets in hopes of making them better.

if you ever come across some good pellets, there will be nothing you can do to them to make them shoot better. I have lots of good pellets because I know they exist and I’ve spent a lot of time looking for them. If you take any of my good pellets and shoot them in a competition out of a good gun you will not have any fliers. How do you know when you have good pellets….believe me, you will know. I’ve said this a hundred times and most won’t hear it because they have never had good pellets, and if they did their equipment was not up to the task of fully utilizing them.

BTW….if you weigh, head sort, or do anything else common to the sorting folks..,,you will find that the good pellets that shoot perfectly don’t all have common head sizes or weights. For all intents and purposes…they appear just like any other bunch of pellets. How can this be? Nobody knows. I just know they exist and if I’m going to shoot a competition that requires me to use pellets….I’m going to find them.

Now, if you are buying some complete crap and shooting them through some oddball barrel that is at the fringe of tolerance….maybe sorting will exclude some flyers for you. I’m personally not at all interested in mid level performance so I don’t dabble in that.

That’s the best piece of information I can give…but I’m sure it will mostly fall upon deaf ears. Believe what you like.

Mike



some very good advice here


mike was clearly not refer9ng to the original poster here, he was referring to lads, chaps or casual competitors in general

there is a great difference between competing and competing at the highest level

only those with an open mind or those that have some critical thinking ability will fully understand mikes comments

as someone who has competed successfully in short range centerfire benchrest, long range f-class and others at a world championship level for decades

I know very few competitors REALLY UNDERSTAND THE FINE DETAILS it takes to win

as someone who has designed a srbr stock the JTR, rear bags for shooting and other neat stuff it is only a very few who truely understand the particulars 

of what it takes to make the combination of pellets, barrels, rifles and lastly YOUR OWN BODY in,harmony to achieve the results we all dream of

10 meter air rifle rifle adjustments come to mind, ost don’t understand the intricacies between rifle and body

this same complexity of understanding of how things work can be applied to the attempts to solve sorting issues

to shoot a very very accurate combination of rifle and ammunition is exciting 

when you set records after it happens you say THAT WAS EASY. and it is when it all comes together

IF YOUR EQUIPMENT IS OT THE BEST how can you properly evaluate pellets? and more so if your not up to the task

could go on but the point was mike was stating or attempting to state factual information to help those who wish to understand

have not seen him direct any criticism towards the op, although wish the op would open his mind to the information r at her than get offended at mere suggestions of a different interpretation of data

thst my friend is hard to do,and I am still struggling with it when I am proven wrong from time to time

good thread and some great information here 

jeff

 

[dan_house]

I found about the "Yrrah Roll" when I first got into field target in 2010, or 2011. I was shooting a bone stock Mrod, with Crosman 7.9's out of a tin. I was looking for any advantage I could find, that I could do in my kitchen or workbench at the shop. Weighing and rolling was one such process I could do and had the stuff around to do it. It decreased my flyers noticeably, group size did shrink a tad. 

It increased my consistency, it did NOTHING to increase my score.

Blasting starlings will not benefit from this process, hitting a 1.5 inch KillZone at 55 yards might. My goal was to eliminate variables, and for me personally, that's all I expected from it. Again, putting rounds on target is on me, not the gear (assuming yer gear is dialled and ready).

"This thread was just the beginning of an effort to put to bed anecdotal information with real data"

Im pretty much convinced that short of having some one like NASA or ISO run these tests (and alot of them) we will never put it to rest. Why? see below

" But like I said, seriously, anyone that wants to repeat the tests should easily confirm or refute the numbers I posted."

Issue I see is the huge variety of pellet and gun combinations, being shot in controlled and non-controlled conditions and environments(Mike's range in CO, LD's tunnel in CA, Baker's test at their shop). Getting an "apples to apples" comparison will be darn near impossible. Mike's environment in CO is similar to mine in MT, someone doing this test in say, Central Florida might see different results. Air temp, air density and humidity will affect any test to some degree (IMO those factors should be listed when you publish yer results of these tests...). As Cornpone noted, folk's test rigs will vary (back to NASA and ISO....) so that's another layer of "noise" to affect/skew the results. Another layer of "noise" is my skill level vs someone like Mike N., even shooting the same gun at the same range in the same conditions.

 

[Therealld]

"A mike can NOT accurately measure those diameters, it really takes a “tri-mike” to do it,"

What about a pelletgage?

Assume for the sake of argument that a 4.51 head diameter is "perfect" for YOUR barrel. The available lead engages concentrically when seated and seals fully. Introduce a 4.52 (or larger) head diameter. As many have noted, the barrel will "size" the pellet. What would that "sizing" do? Seems it would take the additional lead and squeeze it into the space available. Would that increase the contact area between pellet and barrel? Seems it would. Would that increased contact area increase friction? Seems it would. Would the larger diameter pellet weigh more? Maybe, maybe not. But it might. Could any increased friction and additional weight effect muzzle velocity? Seems it could. How would the different shape created by the "sizing" of the larger diameter pellet effect the pellet in flight in comparison to the "ideal" size pellet? 

Would the larger diameter pellet "roll" to the same spot? If head and skirt were larger by the same amount then it seems so.

Is any of this actually relevant and usable? Probably not.

Somewhat





I abhor replies with multiple questions and multiple choice answers.

 

[bandg]

"A mike can NOT accurately measure those diameters, it really takes a “tri-mike” to do it,"

What about a pelletgage?

Assume for the sake of argument that a 4.51 head diameter is "perfect" for YOUR barrel. The available lead engages concentrically when seated and seals fully. Introduce a 4.52 (or larger) head diameter. As many have noted, the barrel will "size" the pellet. What would that "sizing" do? Seems it would take the additional lead and squeeze it into the space available. Would that increase the contact area between pellet and barrel? Seems it would. Would that increased contact area increase friction? Seems it would. Would the larger diameter pellet weigh more? Maybe, maybe not. But it might. Could any increased friction and additional weight effect muzzle velocity? Seems it could. How would the different shape created by the "sizing" of the larger diameter pellet effect the pellet in flight in comparison to the "ideal" size pellet? 

Would the larger diameter pellet "roll" to the same spot? If head and skirt were larger by the same amount then it seems so.

Is any of this actually relevant and usable? Probably not.

Somewhat





I abhor replies with multiple questions and multiple choice answers.

Just read the short ones.

 

[Therealld]

I'll admit I've been reading this and reading about the rolling... And I don't get it. Yes, you roll the pellets down a shallow slope and they curve. So this appears to give you a skirt to head diameter differential between pellets. But what exactly does that do for you? Someone educate me in this???

Seriously, I'd like to hear your opinion @yrrah and @Therealld and @thomasair ... Is there a discriminant you can think of which we could use to exploit the sorting this test does? I am tired of butting heads with people who really aren't interested in the test. Did someone come up with a discriminant back when the argument was kicked around on the "yellow"?

Thanks for your patience guys.

I tried the roll test before Harry posted about it, as someone else (a Brit I think) was using it in the 80s. I tried it, and tried to like it, but found it did little for my accuracy except identify the Pee-Wee pellet skirts that were the bane of the best pellets of then day, the Crosman 7.9 (the Premier heavy version wasnt even being sold yet). But everyone had pretty much resorted to sorting out pee-wees with a slightly oversized sizing die and sometimes (I know I did) a weigh-sorting process as well.

I realize many shooters then and a few now do use sizing dies to “uniform” their pellet skirts and even head and skirt, but most of my guns don’t “like” die-sized pellets.

Now to me few shooters are interested in more in numbers and conjecture to the point he picks the known worst ammo to test a method that is intended to improve accuracy, but different strokes, right?

I studied for years to try to solve airgun accuracy issues, and it was clear that a good gun/scope combo was ultimately limited to the pellet characteristics. Eventually, I decided that MOST apparently well-made pellets suffer from small errors in concentricity between skirt, waist, head, and base cavity. I was able to take samples of the most consistent weight pellets with no visual defects and compare the concentricity of most features by carefully mounting them on a precision pin (custom ground to fit the average base cavity well) and rotate is while comparing the image relative to a custom template on a 100X optical comparator (a fancy shadowgraph). By selecting a sample with the least concentricity variability and using it’s image as the exemplar by carefully tracing the edge profile shape on a mylar screen, I managed to select a sample of the “best f the best”.

The ultimate concentricity sample was the fired in my best airgun at the time (Air Arms Shamal) with outstanding grouping at fifty yards in light wind. 

However when I retired, the huge, expensive J&L setup I had for occasional use wasn’t available. The best way to do this sort of testing is to pull a cell from any batches of pellets you already generally prefer, than try to buy a large quantity of ones in the best cells.

 

[Therealld]

I may be totally wrong about this and it may have already been mentioned...

Would you not need to measure the overall length of each pellet as well? 2 pellets with exactly the same head and skirt diameters, but differing overall lengths will roll a different arc, won't they?

Not that simple! The rolling contact at the max head dia is often quite some distance from “top” of the head, so a pellet of say .200” long may have the head dia contact patch maybe .050” farther back, making the angle more than you may think. But it unknown for now how much the contact patch distance might change among individual samples.

 

[Guest]

I'm uploading a video which may be interesting unless you have already made up your mind (That last was not aimed at YOU).

https://www.youtube.com/watch?v=KLUvpbSzS1g

But in case you don't have time for the video and/or don't understand the proof ...

The test as it is commonly performed does not classify anything about the pellet. It is a measure of how well the user can roll a pellet with extreme consistency. 

 

[Guest]

"A mike can NOT accurately measure those diameters, it really takes a “tri-mike” to do it,"

What about a pelletgage?

Assume for the sake of argument that a 4.51 head diameter is "perfect" for YOUR barrel. The available lead engages concentrically when seated and seals fully. Introduce a 4.52 (or larger) head diameter. As many have noted, the barrel will "size" the pellet. What would that "sizing" do? Seems it would take the additional lead and squeeze it into the space available. Would that increase the contact area between pellet and barrel? Seems it would. Would that increased contact area increase friction? Seems it would. Would the larger diameter pellet weigh more? Maybe, maybe not. But it might. Could any increased friction and additional weight effect muzzle velocity? Seems it could. How would the different shape created by the "sizing" of the larger diameter pellet effect the pellet in flight in comparison to the "ideal" size pellet? 

Would the larger diameter pellet "roll" to the same spot? If head and skirt were larger by the same amount then it seems so.

Is any of this actually relevant and usable? Probably not.

Somewhat





I abhor replies with multiple questions and multiple choice answers.

Just read the short ones.

Hooooo hooo ho ho ... ROFLMAO No insult intended to @Therealld ... @bandg don't zing me with that one if you get a chance ... it's a burner

 

[Guest]

I'll admit I've been reading this and reading about the rolling... And I don't get it. Yes, you roll the pellets down a shallow slope and they curve. So this appears to give you a skirt to head diameter differential between pellets. But what exactly does that do for you? Someone educate me in this???

Seriously, I'd like to hear your opinion @yrrah and @Therealld and @thomasair ... Is there a discriminant you can think of which we could use to exploit the sorting this test does? I am tired of butting heads with people who really aren't interested in the test. Did someone come up with a discriminant back when the argument was kicked around on the "yellow"?

Thanks for your patience guys.

Now to me few shooters are interested in more in numbers and conjecture to the point he picks the known worst ammo to test a method that is intended to improve accuracy, but different strokes, right?

Yes, that seems odd, until you consider the fact that I elected to use a springer (a damn good springer) to perform the test and I already knew that rifle was capable of 1.2 MOA at 25 meters... Then it makes sense to use the worst pellet you can find to see if you can improve accuracy.

First prove the concept (if possible), then apply it. No point in applying it if it doesn't work, right?

 

[Guest]

Ok guys, I think I have had enough fun for tonight. You guys really are a brilliant resource. There must be a couple hundred years worth of expertise reading this thread or not depending upon whether or not someone had made up their mind (that was not aimed at anyone, you can tell because I did not say YOU).

So I am redesigning the darn machine now. I need to figure out how to make it easier to hit the same cell everytime with the same pellet. If I can do that THEN maybe I can collect some VALID data.

 

[BackStop]

I may be totally wrong about this and it may have already been mentioned...

Would you not need to measure the overall length of each pellet as well? 2 pellets with exactly the same head and skirt diameters, but differing overall lengths will roll a different arc, won't they?

Given that some may have misinterpreted the meaning of my post above, let me clarify.

I was actually wrong about the overall length of the pellet. I should have said the distance between the extreme diameters of the head and skirt.

Another clarification, I don't think it is possible to *easily* control for all of the variables that influence the roll technique, therefore I don't think it is a valid test.

However, for those who use it and find some benefit, I won't be the one to say it does not benefit you. To each their own. (smile)

However, those benefits are hard to quantify other than anecdotally. And that is what I think Cornpone is trying to do. Eliminate or control for the variables to the point where the roll test can be easily quantified and duplicated with consistency.

I just don't think it is possible to do it to the point where the test is actually reliable.

Don't get me wrong. I applaud Cornpone for trying and I appreciate his conscientious effort, but I simply don't think the variables that will make the roll test invalid can easily be overcome by most people. And if it can't be done reliably by the average person with true accuracy, why do it at all? That is the reason why I don't do it.

I sort for obvious defects. Then I shoot. Sometimes I get a box or tin of pellets that shoot crappy. Sometimes I get a box or tin of pellets that shoot extremely good. For some guns I have found that lightly lubing them helps. For others, it made no difference in accuracy.

So far, I have not seen anything that the roll test might provide that is worth my time.


To Cornpone, I admire your tenacity and appreciate your efforts. I am not denigrating you or your attempt to prove/disprove the rolling technique. I simply don't see the value in the technique because there are so many variables that can not be easily/simply controlled for.

Kerry

 

[Guest]

I may be totally wrong about this and it may have already been mentioned...

Would you not need to measure the overall length of each pellet as well? 2 pellets with exactly the same head and skirt diameters, but differing overall lengths will roll a different arc, won't they?

Given that some may have misinterpreted the meaning of my post above, let me clarify.

I was actually wrong about the overall length of the pellet. I should have said the distance between the extreme diameters of the head and skirt.

Another clarification, I don't think it is possible to *easily* control for all of the variables that influence the roll technique, therefore I don't think it is a valid test.

However, for those who use it and find some benefit, I won't be the one to say it does not benefit you. To each their own. (smile)

However, those benefits are hard to quantify other than anecdotally. And that is what I think Cornpone is trying to do. Eliminate or control for the variables to the point where the roll test can be easily quantified and duplicated with consistency.

I just don't think it is possible to do it to the point where the test is actually reliable.

Don't get me wrong. I applaud Cornpone for trying and I appreciate his conscientious effort, but I simply don't think the variables that will make the roll test invalid can easily be overcome by most people. And if it can't be done reliably by the average person with true accuracy, why do it at all? That is the reason why I don't do it.

I sort for obvious defects. Then I shoot. Sometimes I get a box or tin of pellets that shoot crappy. Sometimes I get a box or tin of pellets that shoot extremely good. For some guns I have found that lightly lubing them helps. For others, it made no difference in accuracy.

So far, I have not seen anything that the roll test might provide that is worth my time.


To Cornpone, I admire your tenacity and appreciate your efforts. I am not denigrating you or your attempt to prove/disprove the rolling technique. I simply don't see the value in the technique because there are so many variables that can not be easily/simply controlled for.

Kerry

This may well be exactly what we find out. I have managed (on the second iteration of a release device) to reduce the error rate in rolling to 6 percent. I think (hope) this next iteration will halve that. If it does, we should have valid data by Monday evening (on how well we can differentiate the pellets one from another. Then I'll shoot again on Wed and by Thursday this experiment should be in the bag. 

I think you for your well thought out and reasoned post, sir.

 

[BobS]

I tried the pellet gauge. The problem I found was if the head shape wasn't true then the pellet could drop into a smaller gauging hole and the next size up gauging hole. It became very time consuming. What I did like was an air gauging system to measure head size. A friend of mine and a good competitive target shooter uses one and we gauged a tin of mine and sorted them by air pressure results. I put a chrony up and the pellets that gauged higher (more pressure - larger head) had a faster fps and shot little higher. The lower gauge conversely shot slower and a little lower. The theory behind it I believe is that the smaller head size doesn't allow as much air pressure to build up behind the pellet vs the larger head size. I have little knowledge of the science behind it but I can say the end result seemed to agree with the theory for me. For everyday shooting probably not a frugal purchase but for competitive target shooting any help I can get I'll take.

 

[BobS]

That was an awesome video. Thank you. I'm waiting for you to come out with a mechanical pellet release system. I'm your first customer -count me in. And thanks for putting so much time and thought into that exercise. Bob