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Big bore barrels and effect on velocity?

Discussion in 'Uncategorized Threads' started by Neil Winston, Sep 12, 2007.

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  1. Neil Winston

    Neil Winston Well-Known Member

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    We need to know your choke and the actual numbers, Biff. The question: "Is this more consistent than that?" - when "this" can be a gun, wad, primer or whatever - is very hard to answer in any case and without the numbers, impossible. Probably impossible using a single light-operated chronograph anyway.

    Neil
     
  2. halfmile

    halfmile Well-Known Member

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    The Chrony is not a real precise instrument.

    I found mine to be best when I fired 6-7 shots, and threw out the high and low, averaging the rest.

    I sometimes get real erratic readings and have learned to ignore them.

    That said, I want to add add that .745 is not a real "Big Bore" per se, Stan Baker's were .760. I guess I would call it an overbore.

    More than .760, after I talked to a couple guys with radical overbores, have sealing issues and wad selection was crucial.


    In addition, I did find that it was quite an issue to make shotshells that were identical in every respect, even once fired with weidhed charges would have variations.

    HM
     
  3. superxjeff

    superxjeff Active Member

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    Velocity increases on average about 45 to 50 FPS sometimes a little more and some times a little less. The best thing is the increase in pattern density as that is what will give you more broken targets or dead birds. The truly amazing thing about Big Bore barrels is how they pattern large shot. I suppose some wads will not seal as well( Windjammers seem to have a problem) I have never had any issues with federal 12s3, Winchester WAA12, or Remington wads. Jeff
     
  4. Neil Winston

    Neil Winston Well-Known Member

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    Biff, your plan is fine and just reloading them on a MEC is likely to give you as consistent shells as you are going to be able to buy anyway. The trouble is the full chokes you are using. They read too inconsistently to tell the guns apart using the kind of test you are doing. Cronys work fine, as well as anything of that general kind.

    Say you had two of them, mounted on a steel rod about a foot apart. With a cylinder choke you would get this kind of result. Below are two columns, first crony on the left, second on the right.

    1200 1205

    1203 1207

    1210 1208

    1206 1209

    1212 1212

    That's a typical result. Both reading close to each other one faster, then the other.

    But with your full choke you will get more like this:(same shells, by the way)

    1230 1210

    1210 1211

    1209 1230

    1220 1238

    1225 1205

    Here the speeds are higher and are far more variable. The left looks more consistent, but once you have both, you see it doesn't mean anything. All the speeds just have some random number added to them and if the string of random numbers has little variation so do the speeds, but it's all chance, basically, the variability part.

    In "real" testing I've seen no particular difference in 0.72x and 0.74x bores in terms of speed-consistency.

    Neil
     
  5. bigclown

    bigclown TS Member

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    A man with one watch knows what time it is...one with two is never sure. (anonymous) Sorry for my dumb humor on a serious thread. Best Regards, Ed
     
  6. bigbore613

    bigbore613 Active Member

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    I have no problem with my .800 bore factory prototype barrel with Remington wads. My question is I purchased my K-80 barrel in 1992 from John Allem. There were only 2 made for the shot show that year according to him. Does anyone know who has the other one? And yes it is a Factory barrel. Jeff
     
  7. Little Limber

    Little Limber TS Member

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    May I be excused from class? I need a drink.

    LL
     
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