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Can anyone explain why these chokes work?

Discussion in 'Shooting Related Threads' started by bodybuilder, Jul 24, 2009.

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  1. bodybuilder

    bodybuilder TS Member

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    I have a Remington 11-87 trap made in 1989 it came with one choke tube a Trap full which shoots fine but I can also put in regular Remington chokes and they shoot good to. The best pattern comes from one of their newer chokes a singles choke with .27 constriction the Trap full is supposed to have .13 constriction but all chokes seem to give good patterns like they should a regular full does fine, so the gun is either backbored or not making the use of some of these chokes odd. I should mention I have a Remington 870TC made 1n the late 80's that also works with all chokes. Just an interesting question.
     
  2. mixer

    mixer Well-Known Member

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    .13 constriction doesn't sound like it should be a full choke, sounds more like a modified or improved cylinder. .27 is more like a full. Take them both to a patterning board to check the patterns.


    Eric
     
  3. bodybuilder

    bodybuilder TS Member

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    I have patterned both of them and the Trap full is tighter, I did'nt know it had a .13 constriction until I looked on the Remington web site.
     
  4. Brian in Oregon

    Brian in Oregon Well-Known Member

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    The 1187 trap barrel is backbored. Instead of a nominal .727" bore, it has a .745" bore, which tapers to .727" just before the choke tube section. That means it has a nominal .018" constriction already built into the barrel.<br>
    <br>
    When you install a choke tube, you have to ADD .018" to whatever constriction the choke tube has.<br>
    <br>
    A regular mod choke, for example, has a .018" constriction. When installed in the backbored barrel, you have to add its constriction of .018" with the existing constriction in the barrel of .018", giving a TOTAL of .036" constriction. This means your mod choke effectively becomes a full choke when installed in the backbored barrel.<br>
    <br>
    Remington made a special set of choke tubes for this barrel that took the guesswork or the math work out of it. These tubes already take into account the built in constriction.<br>
     
  5. phirel

    phirel TS Member

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    targetmaster- It may not have a 0.013 inch constriction. I suggest measuring it.

    Pat Ireland
     
  6. ExFedex

    ExFedex Active Member

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    One of the best articles ever written on chokes and bores came from our own AveragEd aka Ed Clapper. His July 2003 article in Shotgun Sports magazine explains what Remington did with those overbored barrels and the choke designations that appear confuseing at first. After reading his article you will see what great barrels they are. Perhaps a search of Shotgun Sports magazine archives will find it for you. regards; Bill H.
     
  7. Leo

    Leo Well-Known Member

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    I had an 11-87 trap and I believe Brian in Oregon explained it correctly. The regular chokes screwed in but acted differently than they were marked. The "trap full" choke that came with the gun would hammer targets at any yardage.
     
  8. GW22

    GW22 Active Member

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    LOL, you don't check constriction on a web site -- you measure it. Every manufactured product has tolerances and errors. Web sites contain errors too.

    -Gary
     
  9. sliverbulletexpress

    sliverbulletexpress TS Member

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    If the barrel is 727 before the choke a .013 choke will be 727-13 no matter what happened on down the barrel. True backbored barrels are bored all the way to the choke so you have to make sure you measure the bore before you buy chokes to get what you want. My 1100 classic trap is backbored and uses different chokes than my other 1100 trap that has the standard bore.
     
  10. Brian in Oregon

    Brian in Oregon Well-Known Member

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    silverbulletexpress, regardless of what you have done to your particular barrel, the factory Rem 1187 is backbored, and has a built in constriction of .018 ahead of the choke tubes. This .018 step must be taken into account when selecting choke tubes. It cannot be arbitrarily dismissed as not having any effect on total choke constriction.<br>
    <br>
    Remington is currently making an overbored, not backbored, 1100 barrel that uses larger choke tubes than the Rem chokes. These are called Pro Bore chokes. This is because their overbored barrel does not have a built in constriction before the choke tubes.<br>
    <br>
    I would suspect, from the description you gave, that your barrel may be similar to their overbored barrel with Pro Bore chokes.<br>
    <br>
    Note that Remington choses to use the word "backbored" for barrels bored oversize that have a step back to normal bore size before the choke tubes, and the word "overbored" for those barrels bored oversize that have no step back to a normal bore, but rather use larger outside diameter choke tubes.
     
  11. OLD ONE EYE

    OLD ONE EYE Well-Known Member

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    They also made 1187 backbored barrels with fixed chokes. I have a 28 inch steprib target barrel with 745 bore and a fixed full choke with 41 thousands constriction. Now if I point it right it is very impressive. Brian is correct Remington was concerned about people putting wrong chokes in the barrels so they constricted the barrel ends down to standard bore size so all their chokes would fit and not be a libabilty issue. The wrong chokes are way to tight in the backbored barrels.
     
  12. Stan B.

    Stan B. TS Member

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    This will explain it...maybe... Data compiled from the Remington web site. I included all the 12 ga choke specs, except Hevi-Shot specific tubes, the so you could compare constrictions between the std bore vs the over bore

    REMINGTON CHOKE SPEC's

    first number = nominal bore diameter
    second number = choke tube diameter
    third number = constriction

    12 GAUGE

    Full (Steel or Lead) 0.727 0.691 0.036
    Modified 0.727 0.709 0.018
    Improved Cylinder 0.727 0.718 0.009
    Extended Rifled 0.727 0.718 0.009
    Rifled 0.727 0.718 0.009
    Improved Skeet 0.727 0.725 0.002
    Skeet 0.727 0.732 -0.005


    Sporting Clays (Extended Nickel-Plated)

    SC Modified 0.727 0.708 0.019
    SC Lt Modified 0.727 0.713 0.014
    SC Improved Cylinder 0.727 0.718 0.009
    SC Skeet 0.727 0.723 0.004


    Sporting Clays (Extended Blued)

    SC5 Full 0.727 0.691 0.036
    SC4 Modified 0.727 0.709 0.018
    SC3 Improved Cylinder 0.727 0.718 0.009
    SC2 Improved Skeet 0.727 0.730 -0.003
    SC1 Skeet 0.727 0.735 -0.008


    Trap (New Style)

    Long Handicap (Lead Only) 0.727 0.686 0.041
    Mid Handicap (Lead Only) 0.727 0.693 0.034
    Singles (Lead Only) 0.727 0.700 0.027


    Trap (Old Style / pre-2000)*
    based on the built-in 0.018" barrel constriction plus(or -)
    the RemChoke constriction
    bore diam choke tube total constriction
    Super Full Trap (Lead Only) 0.745 - 0.727 0.690 0.055*
    Extra Full Trap (Lead Only) 0.745 - 0.727 0.709 0.036*
    Full Trap (Lead Only) 0.745 - 0.727 0.732 0.013*

    The 'Old Style' over-bored barrel tapers from 0.745" to Rem's std 12 ga. bore of 0.727 (+/-.003") BEFORE the threads giving a 'built-in' choke of 0.018"....
    Note that the Full Trap(lead only)choke tube has the same negative constriction as the std. bore skeet choke tube.

    I hope this isn't too confusing...

    Stan
     
  13. Dr.Longshot

    Dr.Longshot Banned Banned

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    You better watch which choke tubes you put in the Remington Bbls, you culd be looking at a disaster, putting in the smaller bore tubes in the larger bore Bbls. If this is possible, I don't know I don't own a Remington Shotgun.

    I have seen it happen putting a Beretta Choke tube in a Seminole Beretta Bbl, it blew the end of and split the Bbl, ruined the guys bbl and did not not want buy him another Seminole Bbl.



    Gary Bryant
    Dr.longshot
     
  14. sshotshell

    sshotshell Member

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    Thanks Stan B. A most complete and fact filled explanation of a choke system that had confused me every time I tried to understand it. Now how does "Lewis Class" work? J.P. Felice
     
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