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???? question for Neil Winston

Discussion in 'Uncategorized Threads' started by Neil Winston, Oct 30, 2008.

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  1. Neil Winston

    Neil Winston Well-Known Member

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    Nick, I just take Dr. Ken's word for it, since we have discussed it a couple of times.

    The determination of shot speed is a function of the instrument used as much as the shot speed itself. Take the 35P. As choke increases, so does shot speed (and this is probably true, at least for some of the pellets near the front of the cloud.) Take an (industry standard) inductive chronograph and tighten the choke and the speed goes down, probably due the the different shape of the shot cloud.

    All in all, it makes little difference. You'd be amazed by the variation in average speed between similarly-marked shells of any brand. With an inductive chronograph, which tells you best what's going on, if you test seven lot numbers of lights and seven of heavies, any brand, you are going to get at least one "crossover," that is a light that is faster than a heavy or the other way around. That's why you can't "standardize" a chronograph with an example factory load.

    But it makes little difference. Really, if you follow some recognized reloading guide, and use some standard powder (I use Red Dot) and use brand-name stuff and a scale and care, in an evening you can make all the "standardization" loads you will ever need in a decade of testing. Before you start some test, just shoot a few and they will be about like they were last time. If they aren't start again. Or another day. Sometimes light-operated chronographs just don't work right and you just have to wait until next time.

    My version - the long one - is at the above link. But no one need to do all that.

    If you follow a guide, you will get about what you expect. If you test your product made according to some text with a cylinder choke and everything chronowise works about right, you will confirm your expectations. If you shoot a full choke instead you will get higher speeds and so much variability that you won't be able to pick up reloading problems which sometimes creep in which is why cylinder choke is better if you have one available. Mod is borderline. Full is useless (for testing variability) and my tests with two good chronos mounted in a line, clocking the same shot, confirm this.

    A couple of shots, full choke - which is what practically everyone does, face it - is a waste of time and shells; shoot them at targets instead and don't worry. If you follow a guide, you'll be OK an any case.

    In other words, the few FPS differences I get are just what you'll - or anyone - get. They are no problem. The shot, after all, doesn't know its speed is being tested and if it's OK, that is, nothing tricky, then I just run with it.

    But, you ask, how about when I want to do something tricky?

    Don't. There can be some surprises at the upper range of pressures which don't show up as changes in speed. This trips up the occasional factory; for the home loader with a consumer chronograph and no pressure pressure barrel it's just an invitation to show up here in another, unfavorable, context.

    Neil
     
  2. Neil Winston

    Neil Winston Well-Known Member

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    Bill, I did, with Pheasantmaster's considerable help, a test of Red dot and Green Dot loads of the same shot weight (same shot bags, actually) and same speeds. I didn't think there would be any difference but:

    [​IMG]

    and

    [​IMG]

    I always say that this is provisional pending replication and I can hardly believe it myself but there it is.

    Neil
     
  3. BDodd

    BDodd TS Member

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    I, too, use a 35P and my methods have morphed some from original. For a very long time, I arbitrarily would reduce readings by 35 fps as a general method to cover the 2 to 5% reduction suggested for shot shells. This necessity seemed bothersome to me in keeping records in the 'puter. I also found that the barrel length, choke, temps, and distance from the first screen made a significant difference often. What I later discovered was that with my 28" barrels and skeet/skeet tubes on my over/under, I could come very, very close to that alleged speed marked on boxes of factory shells. This fact permitted me to use that gun, barrels, and tubes to be my test equipment for all loads and I took the readings at face value.

    Later yet, I started thinking who the heck cares what the actual velocity is when all one needs to do is use their tournament gun, barrel, and choke as they would in competition and test a factory load that the shooter wishes to replicate and then test loads to match the reading, whatever it might be, against the factory load. This, of course, was just a convenient generality for my purpose and wouldn't satisfy the scientific mind of folks like our Sir Neil. But you might try this method for simple comparisons of your loads against factory shells.....breakemall.....Bob Dodd
     
  4. Dove Commander

    Dove Commander TS Member

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    Neil, why would Green Dot perform better than Red Dot? Pressure? Setback?
     
  5. phirel

    phirel TS Member

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    Neil's results describing Green Dot v. Red Dot have been duplicated several times over many years at first the Hercules plant and not the Alliant plant.

    Dove Commander- You asked an excellent question, but I believe the only answers you will get are not much more than guesses. The only real thing I can see between Red Dot and Green Dot is that Green Dot reaches its peak chamber pressure about 3/10,000 of a second slower than Red Dot. Converting this observation to an improved pattern can only be done with speculation.

    We can form a sound conclusion from these data. That is, Green Dot is great for handicap loads. Another sound conclusion one can reach is that not everyone who shoots Green Dot for handicap will consistently shoot good scores. I can furnish proof for this last conclusion. I shoot Green Dot for handicap.

    Pat Ireland
     
  6. DC

    DC TS Member

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    Cold weather! Red Dot 6's 1 1/4 works Great! Patterns Well! Breakem All! Hood too the Wood!! Cheers! & a Kind Wish!
     
  7. Shooting Coach

    Shooting Coach Well-Known Member

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    Dear Pat

    I use Unique for Handicap loads, and have noted that it will also occasionally miss a target.
     
  8. Brian in Oregon

    Brian in Oregon Well-Known Member

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    Now that's interesting.... shot behaving per the Gerlich principle.<br>
    <br>
    I always assumed shot would slow down in a tight choke due to increased friction and raise pressures. Instead, it appears it accelerates as the base gets smaller, which is exactly the Gerlich principle.
     
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