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Thread: M2 Shims, how to adjust it?

  1. #1
    Join Date
    Aug 2008
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    Western Wisconsin
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    Default M2 Shims, how to adjust it?

    I bought an M2 with a 21" barrel last winter, and I thought I would shoot some trap with it. My shotgunning background is about zero, having maybe shot 600-700 rounds in my entire 58 years.

    Posted here asking after 28" barrels and then found that Impact Guns has them for $400, plus shipping.

    I understand how to use the shim system, that is where to put parts 6 and 7. What I would like to have explained is how to determine what I need to do.

    How do you check to see what adjustment is required?

    Then which shims move the adjustments which way?
    Yours in Marksmanship,


    Michael Carlin


  2. #2
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    ABQ
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    http://www.gunnersden.com/index.htm....-patterns.html
    go down to #3 and get a plain white piece of paper and a stick pin and a 15" ruler and draw you a 30" dia circle with a string and follow directions!
    Last edited by HOGWILD; 08-18-2008 at 12:26 AM.

  3. #3
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    Aug 2008
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    Western Wisconsin
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    Hogwild,

    Maybe I should restate my question. In fitting the stock to me, how do I determine which way to move the pattern and which shims will move it that direction.

    I understand that choke effectiveness is measured in a 30" circle and that counting the number of shot in each segment 1A through 4D will tell me if the barrel is evenly distributing the shot in the pattern.

    My question is how do I fit the gun to me?
    Yours in Marksmanship,


    Michael Carlin


  4. #4
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    Elk Grove, CA
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    Default

    Quote Originally Posted by MICHAEL CARLIN View Post
    Hogwild,

    Maybe I should restate my question. In fitting the stock to me, how do I determine which way to move the pattern and which shims will move it that direction.

    I understand that choke effectiveness is measured in a 30" circle and that counting the number of shot in each segment 1A through 4D will tell me if the barrel is evenly distributing the shot in the pattern.

    My question is how do I fit the gun to me?
    Here's how it's supposed to work in general:

    If you don't use the beads, which many wingshooters do not, you may be able to change the shims to move your POI around. The drop shims can change drop, the cast shims can change cast.

    I believe ZZ offers the least drop and C offers the most drop.

    What many do, myself included, is to place large paper targets out at a reasonable range, say 25 yards, and just place a small dot in the middle of the large blank target. From a standing position, take a fairly quick snap shot at the small dot. Maybe do this 3-4 times w/o looking at your pattern closely. Long rolls of butcher paper are great for this.

    This should give you an idea of where your gun patterns when you are shooting it.

    If you want to change the POI, work with the shims accordingly.
    mudhen - CA

    "Lighten up Francis"

  5. #5
    Join Date
    Aug 2008
    Location
    Western Wisconsin
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    Mudhen,

    Thanks, if the pattern is too low do I want more or less drop to correct it? If, as I suspect, I am missing to the left do I want to cast on or off to move the pattern to the right?

    Thanks again for you response.
    Yours in Marksmanship,


    Michael Carlin


  6. #6
    Join Date
    Oct 2006
    Location
    Georgia
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    Default

    More drop will lower your pattern. More cast will move your pattern right.Cast Off is for most right handed people. Cast on is for lefties and cross dominant eyed folks, ie right handed, but left eye dominant.
    Here's what you do. Take your gun out to a pattern board. Usually a skeet, trap, or sporting clays range will have one, or use butcher paper, a big cardboard box, posterboard ect with an orange target dot. With both eyes open mount your gun quickly to your cheek and shoulder and fire. Do this about 10-15 times with a MOD choke at 25yrds. Be sure and start with the gun unmounted. Mount your gun and fire within a second or two like your going to shoot a bird. The gun should shoot where your looking if you mounted properly and the gun fits.
    If the gun shoots low, then you need a thinner shim. If your high, use a thicker shim. What most shooters want is a 60/40 pattern. Where 60% of your pattern is high and 40% is lower. Be sure with the locking plate (the part thats heavy and goes in the stock) to use the corresponding plate that matches the shim that you use: 55mm shim=55mm locking plate.
    I liked it when Benelli just used the A,B,C,D shims and plates. That was easier. An A was 50mm of drop, B was 55mm, C was 60mm, and D was 65mm. More, or less, than that and you had to inlet the stock. The shims are also either Cast On, or Cast Off 1/4", or so- not much adj here. Hope this helps.
    Last edited by johnnywitt; 08-19-2008 at 02:18 AM.

  7. #7
    Join Date
    Aug 2008
    Location
    Western Wisconsin
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    Default

    Exactly the information I was hoping for! Thanks!!
    Yours in Marksmanship,


    Michael Carlin


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