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"Fast shells spread more"- do they? (Winston)

Discussion in 'Uncategorized Threads' started by Neil Winston, Sep 9, 2005.

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  1. Neil Winston

    Neil Winston Well-Known Member

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    "Fast shells spread more"- do they?

    “The effect of shot speed on pattern width is known by all but properly exploited by but few. When you need just a bit more spread and don’t want to bother with changing chokes, just slipping in the next “speed group” – say substituting “heavy” for “light” – can give you just the edge you need, with the bonus of extra pellet energy at the target that changing chokes won’t accomplish.

    But you’d best not try this without regard for the physics involved, as thoughtless changes can be more trouble than benefit. Here’s why: pattern development is dependent on air drag, and that drag is not a simple monotonic function of pellet speed, but rather is a function of the square of the speed. So the effect of pattern-widening is magnified at the upper reaches of pellet velocity. Here is an illustrative figure:

    [​IMG]

    And it’s that huge increase in pattern-width at the right side of the graph that can lead the unthinking claysman into trouble. Trying for that last bit of pellet energy for a 60-yard crosser, he loads up with 1400 FPS and pays twice for his mistake: By the time the pattern gets out there it’s often too spread out to even clip off a “visible piece” and the recoil – which he has suffered for no benefit - will affect his shooting for the rest of the day.”

    I pen that last period and lay down my quill, letting my eyes drift back appreciatively over the text. Very good – very good indeed! Beyond just repeating what every reader will agree with, I offer not just scientific causation but even surprising graphical evidence, as well as both support and warning to my readers, which about covers the bases, to my mind. OK, that “instrumental” flourish on the x-axis of the graph might be a bit over the top, but it lends such an air of erudition to the enterprise it’s just too good to pass up. If the response to this article is favorable I may be able to string this out for a couple more issues, dreaming up wad and powder effects, interactions with shot size, whatever comes to mind; you know the drill.

    Time again to reflect how good I have it. An evening in my den in front of the fire, building castles in air for yet another shooting publication. My ever-more-grey-muzzled retriever curled at my feet, napping and no doubt dreaming about the day in the field I promised him next month when I will pretend to test a brace of matched Purdeys. How can you beat it?


    Admit it – you were well into this before you first began to smell a rat. The first parts are so much like what you read everywhere, hear at every club, I dare say they slipped past your BS detector without raising any alarm whatever. So now backtrack and see how far you have to go to find some fact –

    Back 1: the “60-yard crosser” paragraph. Well that was a giveaway, wasn’t it?

    Back 2: The graph. Sure, that’s a graph of squared numbers, but is it possible? I hope you don’t think so!

    Back 4: This is the support for the graph. If it’s nonsense, so is this.

    Back 5, right to the start. Unfortunately, there’s hardly a word of truth in it either. In fact the first 12 words, “The effect of shot speed on pattern width is known by all” are as questionable as any of the other fibs I told.

    Introduction:

    I’ll bet that every reader knows that when you push shot faster the pattern “opens up.” But what happens when I now ask you “How much?” On the off chance that you have an answer to that, I keep another question in reserve: “How do you know?”

    This article will cover an experiment involving shot speed and pattern width. For a limited set of data, it answers those questions which I’ll wager stumped most of you: “How much?” and “How do you know?” Based on data from 10 patterns each from shells measured at 1030, 1130, and 1230 feet per second, it will report some statistically significant differences, and some cases where the “expected” differences failed to appear.

    Properly, this is the first test of patterning which should be done, since it answers the question of how well speed has to be controlled in comparing shells, chokes, powders and so on. If a difference is found is it due to the change in components or equipment, or could shot velocity be responsible for the whole finding? Conversely, if no difference if found, is it speed making a change in one direction and “canceling out” a change in the other, thus masking a real effect?

    The best experiments make you re-examine your ideas, perhaps even change your mind or behavior. This experiment has led me to put some of my MEC bushings away in favor of bigger-numbered, larger-holed ones. With luck, it may change your outlook as well.

    Equipment:

    The critical piece of equipment making this experiment possible was the software program “Shotgun-Insight”, an application which reads digital photos of patterns and analyses them, making it possible to read enough patterns to draw reasonable conclusions from them. The rest of the equipment used: pattern paper, a digital camera with flash and tripod, PC and the rest, act only as support for the program. Kaleidagraph software produced the graphs.

    Method:

    A MEC 9000H was used to load once-fired STS hulls with Red Dot – 15.7 grains, 17.7 grains, or 19.7 grains. With the components used, the resulting speeds were about 1030, 1130, and 1230 feet per second, as measured by an inductive chronograph, and the 10-shot standard deviations of all were under 5, which is consistent ammo indeed. The shot is Remington magnum 8’s with a count of about 440 per load as dropped by a 1 1/8 oz. MEC bar. All shot is from the same bag.

    On a warm day at Metro Gun Club in Blaine, Minnesota, patterns were produced firing a “factory bigbore” Perazzi which has produced consistent full choke patterns in other experiments. The distance used was 34 yards, in an effort to make more use of the “75% diameter” statistic offered by Shotgun Insight. Ten patterns were shot at each shot-speed.

    The digital photos were intentionally overexposed by one stop and a fill-in flash was used; all the resulting JPEG’s were usable.

    Results:

    Here, in bare-bones form, are the results of the test.

    [​IMG]

    Based on averages (mean), the patterns from the 1030 FPS loads were denser in the 0-10 inch and 10-20 inch diameter rings than the others and the 20-30 inch diameter ring was less dense. The innermost-ring differences were not statistically significant (I.E., roughly, they could reasonably attributed to chance) while the others were significant.

    Look, even I see this as something of a letdown. Hours of work resulting in 12 numbers only four of which mean anything? I plan to go on with “How much?” and “How do I know?” to show what’s behind those numbers, but in the end, those are the “experimental results.”

    Let’s look at the data as it comes in, that is, shot by shot.

    [​IMG]

    Looking at the traces from the top down on the graph, the first, the black line and open squares, shows that the pellet count is stable, pattern-to-pattern.

    The green dots, connected by a green line, are the pellet counts in the 10-to-20-inch ring. This count too is quite stable.

    Going on down, we meet the red trace, the pellet count in the inner 10 inch circle, and the blue trace, the 20-to-30-inch ring. They are more variable than the others, and in addition, vary inversely, that is, when one goes up the other goes down. When there are few pellets in the center there are more on the edge and visa-versa, while the 10-20 inch ring just tracks along. No, these pellets are not jumping from the inner to the outer rings, it’s just that even when the total number of pellets in a 30-inch pattern is the same, some patterns are more spread out than others. “Spreading out” means some 1-10 drifting into the 10-20 area and, at the same time, 10-20 pellets drifting into the 20-30 area. The sector with the most pellets is the one from 10 to 20 inches, but since it is 3 times the area of the 10 inch circle, the pellet density is only about 2/3 that of the center. Once again, these patterns are “hot in the center” like all the others intended for trap shooting.

    So what does a significant difference look like?

    [​IMG]

    The shots have been ordered according to total pellets in 30 inches, increasing left to right. The 1030 patterns are the solid markers and lines; the 1130 are outline markers and dotted lines. We see some real differences here. The 1030 FPS 0-10 and 10-20 rings are more dense, less dense in the 20-30 inch ring. So, in fact, increasing the speed 100 fps with this slow start has widened the pattern, much as opening a choke tries, but mostly fails, to do.

    And what do non-significant differences look like?

    [​IMG]

    Here the traces cross and re-cross each other in random ways and are often just the same. In this case, starting from a faster baseline than the first graph, increasing shot speed by 100 FPS did not widen the pattern.

    Another way of looking at this is the “75% diameter” statistic. This is a calculated rather than counted datum which predicts a circle diameter which would contain 75% of the shot.

    [​IMG]

    This is the same story as told by the “rings” analysis. The 75% diameter of a 1030 FPS shell is smaller, that is, the pattern is smaller.

    Just a couple more things. Could I have gotten these results by other means, specifically “by eye” or “side-by-side inspection” or fewer patterns?

    No, and here’s reason 1. There’s too much overlap:

    [​IMG]

    Most of the time most of the rings look about the same across all speeds. You can’t possibly tell more than a couple apart, much less several at once.

    And here’s reason 2:

    [​IMG]

    If I’d shot just the first 5 I’d say that 1130 FPS had a hotter center than 1230. If I’d shot just the second 5, I’d say that 1230 had a hotter center than 1130. It’s only by shooting all ten can I see that there’s really no difference between them at all. You need at least 10 patterns to avoid being misled.

    Discussion:

    Based on this, I’m going to speed up my first-shot-doubles shells to about 1150 FPS from the 1050 FPS range I’ve been using. They are 1-oz. anyway; why not give myself a better chance? I’m going to try Extralites at handicap. Just to see if they are denser – denser enough, that is, to help.

    Is the odd effect seen here related to sub-sonic v. super-sonic? Someone here, maybe it was HMB, made a big deal of that in an earlier thread. Could he have been right? Some evening I’ll settle down by the fire with Kyra at my feet and explain it all for you.

    Yours in Sport,

    Neil
     
  2. JerryP

    JerryP Active Member

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    "Fast shells spread more"- do they? [Winstson]

    "Riveting, from beginning to end."----Kansas City Twister

    "Neil has done it again"--------------Danville Orator
     
  3. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    At the very beginning of this article, I thought Neil had read too many reloading articles written by Rodney Reloader of "skeets" magazine. Good job Neil, well done and to the point for the velocities and distance the patterns were shot. Are we left to assume the high end numbers may be projected farther out, say, 42 yards with even higher velocity loadings while maintaining the same sort of ratio? Probably for singles shooting, an average is real close to 1145-1200 for most shooters would be a guess on my part. For long handicaps, choosen velocities may be somewhat higher as an average? If true, how would the average singles load compare, percentage wise if a higher velocity load were used from the max of 42 yards? Such as the max limit for velocity with either 1-1/8 @ 1290 or 1325 with an ounce? Thanks. Hap
     
  4. halfmile

    halfmile Well-Known Member

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    Neil, you make my head hurt. Just gas that sucker and back it in.

    HM
     
  5. Harold

    Harold TS Member

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    Neil,

    Thanks, that was interesting. For a while I thought I was reading the scribblings of a real gun magazine scribe, and was getting ready to put my hip boots on.

    One thing I didn't quite understand is why you wouldn't just use a more open choke for the first shot of doubles instead of upping the speed.
     
  6. XTBrowningBabe

    XTBrowningBabe TS Member

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    Thanks for sharing, Neil. I'm going to have to re-read it to make sure I absorb it all, but very interesting, nonetheless.

    :eek:)
     
  7. Harold

    Harold TS Member

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    Troy Boy,

    “IT” starts out as a rather clever impersonation by Neil of a typical gun writer’s approach to a topic. He spins an article out of whole cloth based on a theory with no test data to back it up.

    “IT” then turns into a report of a test that Neil did on pattern spread versus velocity. The results are quite simply summarized in the sixth chart which shows the pattern width of shells at 3 velocities, 1030, 1130, and 1230 fps. It probably would have been a little less confusing without all the other charts.
     
  8. N9FZX

    N9FZX TS Member

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    Neil,

    It looks like you used decent quality shot with enough antimony to keep it from deforming. I suspect that the old "faster shot = more spread" story applied to softer lead, which tends to deform in the wad under acceleration, and the deformation is dependent on shot velocity. Deformation, in turn, leads to "fringing" of the pattern, creating a low-density annulus around the main pattern.

    Try some of the more cheezy Federal 1400 fps hunting rounds and you'll see what I mean...
     
  9. Smiley

    Smiley Member

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    Thank you Winston for opening the minds of shooters and introducing them to the science of ballistics.As can be seen there is a lot a person can do to get the best out of your gun,anybody that handloads for a rifle will tell you that the best performance is not in any set criteria within the bounds of safety but is arrived at by trial and error to find the best accurate load that suits your gun .The same holds true with shotshells handloaded or factory loaded,have you noticed that a particular load or brand seems to break the clays better(when this happens it's probably the best load for your gun).
    Thats all for now folks Paul
     
  10. Lee Christianson

    Lee Christianson TS Member

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    Excellent info, and solidifies what I've believed for decades. I have no loads beyond 1250 fps save one, and I tried that last night in 27 yard handicaps using my TM1 special w/extra full fixed choke. The load used was 1275 fps and gave me a little 'fringe' pattern that enabled a few extra hits when I was off a bit.

    I've seen some guys bring loads that approach 1450 or so (turkey shoots) and they can't figure out why they're not breaking birds at 60 yards. I know their pattern's blown up but who am I to say anything?

    At 16 yards my best load is 1 oz at 1150. It just smokes clays when I do my job.

    Still, Neil you should take a break and have a brewski or two.. Even though I'm somewhat well versed in ballistics you've raised the bar a couple of feet.

    Thanks for posting this info. Have a great weekend.
     
  11. zzt

    zzt Well-Known Member

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    Thanks Neil. I do think subsonic vs. supersonic has a big influence in pattern performance. I haven't tested as scientifically as you, but I have noted the following:

    For loads that never exceed the speed of sound, even at the muzzle, patterns are much tighter and more uniform. For loads with 3' muzzle velocities ranging from 1150fps to 1350 fps, pattern efficiency increased up to about 1220fps and then decreased from there. Pattern from any load I tested above 1325fps or so were really poor. All were shot from a fixed choke modified barrel. I've never done this test with any other barrel, so 1220 might have been the sweet spot for that barrel. Anecdotally, 1 oz factory STS @1180fps seem to break targets into smaller pieces than factory 1oz Nitro's @ 1290.

    Andrew, thanks for that great idea. I would never have thought to count pellets that way.
     
  12. Neil Winston

    Neil Winston Well-Known Member

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    "Fast shells spread more"- do they? (Winston)

    Thanks for all the comments. Though Harold has decribed what's going on, I'll fill it in a little more.

    The first few paragraphs are a bit of a trick. Using the literary form "dramatic monologue" it was intended to entertain the careful reader and cue him (and her, BB) to sharpen up his/her critical skills for the rest. Though not exactly Browning (Robert, not John or Babe) , I see that it was accurate-enough parody to misdirect a few a while and they, at least, will concede me journeyman's competence in the genre.

    A few paragraphs of equipment and how it was used follow. Then the results and here's something I should have pointed out: They are all the same, but presented three ways. The first is the table with 4 significant numbers, the 1030 ones. The next section of ring analysis tells the story a different way, and the last, which Harold (and I'll bet Andrew) thinks is the best version, just does it again. My aim was to show that in previous and forthcoming experiments all these ways are valid analytical tools. (aside: my choice of 34 yards finally made the 75% diameter statistic useful, which hasn't worked as well at 40 yards since too many pellets are "lost.")

    The discussion points out that this is not just "all talk;" actual choices of shells flow directly from it.

    The last part is a preemptive strike. I was expecting some objections in the form "I shot several patterns and I could clearly see that..." and these two graphs prove, to me, that "seeing" any of these results (without 10 patterns, without counting) is simply impossible.

    Hap, I referred in the article to a "limited data set" and that's what it is. I make, as yet, no great claim to the generality of these findings. At the Grand I bought Light, Heavy, and Nitro 27 Remingtons and they will be tested next. Then I'll have more to say about this subject. The Shotgun Insight program can recalculate the patterns to other distances. Though I'll have to confirm it's accuracy someday, it sure looks like it works so far.

    N9FZX, I owe Old Cowboy a test of soft vs. hard shot and I'll do it this way, based on your suggestion. Thanks for the observation.

    Andrew, when I loaded the shells my pellet counter gave me 438, 440, 438 pellets and a post test gave me 435, 436, 440.

    I'm headed to the Calf and Steer Shoot so I can't post the exact pellets on paper, but figure 420 for the 1030 shells. the same for 1130, maybe 5 fewer for the fastest ones. This loss of about 20 pellets is a constant at 35 yards.

    Well, it's time to dash. I'll be back...

    Neil
     
  13. Harold

    Harold TS Member

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    Lee,

    There is nothing in Neil's data to suggest that a 1450 fps turkey load would be any worse than your 1150 fps load. You did realize that first graph was a spoof, didn't you?
     
  14. Hap MecTweaks

    Hap MecTweaks Well-Known Member

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    Harold, your right,there's no data in Neils work making such a suggestion. "There is nothing in Neil's data to suggest that a 1450 fps turkey load would be any worse than your 1150 fps load."

    Are you saying that the 1150fps load of number 8s and a load of the same at 1450fps at 42 yards would also follow the same percentage path as suggested by Neils tests?

    Like Andrew, I'd like to see some comparison facts between the 1150 versus 1290 at long handicap yardage such as 42 yards. Hap
     
  15. W.P.T.

    W.P.T. TS Member

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    Ok, so if the leading pellet is going 1250 FPS how fast is the last or slowest pellet in the same pattern going being as there is a drafting effect that has to worked into the equasion, unless it is not in the hot spot of same pattern which would basically eliminate the drafting effect for the most part ... If the target gets hit with the "hot spot" of said pattern is there enough target left for the last pellet or slowest group of pellets to do any damage to, being as the target would obviously be broken by the time the last pellets got there ... By looking at the shot string it should be obvious to everyone that not all pellets are equal and therefore do not all hit the target at the same time ... This is something that most people could care less and never think about but comes into view when counting the X's and O's on the score sheet which is the only time it matters ... The blown pattern effect is good at times and not so good at others depending on if the fringe of said pattern is the part of the pattern that is actually breaking the target and or targets which increases the amount of X's rather than O's on the score sheets ... It would be a guess to figure which is which and would be altered by shooting some shells that are slower than others, not by the recipe but in actuality make the last pellets in the pattern that much slower than the rest or are they or are they not ..? Just a thought ... WPT ... (YAC) ...
     
  16. W.P.T.

    W.P.T. TS Member

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    Ok, so if the leading pellet is going 1250 FPS how fast is the last or slowest pellet in the same pattern going being as there is a drafting effect that has to worked into the equasion, unless it is not in the hot spot of same pattern which would basically eliminate the drafting effect for the most part ... If the target gets hit with the "hot spot" of said pattern is there enough target left for the last pellet or slowest group of pellets to do any damage to, being as the target would obviously be broken by the time the last pellets got there ... By looking at the shot string it should be obvious to everyone that not all pellets are equal and therefore do not all hit the target at the same time ... This is something that most people could care less and never think about but comes into view when counting the X's and O's on the score sheet which is the only time it matters ... The blown pattern effect is good at times and not so good at others depending on if the fringe of said pattern is the part of the pattern that is actually breaking the target and or targets which increases the amount of X's rather than O's on the score sheets ... It would be a guess to figure which is which and would be altered by shooting some shells that are slower than others, not by the recipe but in actuality make the last pellets in the pattern that much slower than the rest or are they or are they not ..? Just a thought ... WPT ... (YAC) ...
     
  17. W.P.T.

    W.P.T. TS Member

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    I put that in there twice so those who do not get a grasp on what it says the first time can read it at a slower pace a second time and maybe understand what its saying ... If so please contact me and tell me will you please ... WPT ... (YAC) ...
     
  18. Harold

    Harold TS Member

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    Hap,

    I am not suggesting that the 1450 fps loads would have the same pattern percentage as the 1150 fps load. I doubt if anybody really knows, because the testing to prove it in a statistically significant way takes too much time, less time now that the Shotgun Insight software is available.

    Like everybody other than Neil, I'm too lazy to do the test, so I'll wait for Neil to do it.


    WPT,

    I read your post both times, still didn't understand it. How do you look at the shot string? It goes too fast for me to see it.
     
  19. phirel

    phirel TS Member

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    A fascinating report, I enjoyed it very much. Thank you Neil. I, like WTP, do have some question about the speed of the shot. One load has a listed velocity of 1130 ft./sec. All of the shot hitting the pattern sheet with this load are grouped into one set and compared to two other velocities. If the 1130 ft/sec is an average velocity of all of the shot in one pattern (or even a modal velocity as is printed on factory boxes), then an accurate statistical analysis of the results may not be quite as simple as indicated in the table presented. When comparing patterns of loads with "average velocities" of 1130 and 1230 ft/sec, some of the individual shot in in the 1130 ft/sec load might be traveling faster than the slowest shot in the 1230 ft/sec load. If the measured velocities are the fastest shot in the loads, the probability of velocity overlap among the different loads is greater and a statistical comparison using only the extreme of the velocity curve of the shot string is not valid.
    Pat Ireland
     
  20. motrap

    motrap Member

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    NEIL, et al....................
    If one wants to know how velocity (or any other variable) affects pellet count, pattern spread, energy, etc ....... all one would have to do is paint each individual pellet with a different color, place the individual pellets in precisely the same location within the loaded shell, and track the performance of each color separately (with time lapse the graphs would be automatically drawn.) Of course, there are consistency factors that would have to be adhered to such as placement of the shell in the chamber, etc., but this method would be foolproof.

    I have contacted Crayola Corp, and they are willing to paint the shot, but do not have 440 different colors, but would be willing to develop more if the demand were there. I am soliciting TS.com users to help make this feasible, as I am excited about breaking 1000 straight in the near future. ......... Rudy
     
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