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O/U shotgun barrel alignment

dannej
I recently patterned three different o/u shotguns, all of quality. Both barrels patterned in the same spot on one shotgun. The other two shotguns had an eight and twelve inch vertical difference, respectively, between the centers of the patterns. Both were centered the same horizontally. The patterning was done at 40 yards. Should the barrels shoot the same or does one barrel shoot higher to compensate for shot drop at forty yards? I didn't pattern them at shorter ranges.....

Thanks for any info!
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Comments

8 comments

Date Votes
  • Tailgunner1954
    So you found 1 good one, and 2 that are not so good. Now you know why you need to shoot the pattern board.
    Try switching chike tubes in the 2 that didn't shoot so good, sometimes it helps.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • dannej
    So it is as I suspected. Thank you for your reply. The good one is an SKB. The others are Winchester and Ruger....
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  • Tailgunner1954
    Like I said, switch the choke tubes around. Bottom to top, gun to gun, different restriction, etc. If the problem remains consistant, with the various combinations, than blame the gun.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • dannej
    I will definitely give it a try. The Winchester I have had for about twenty years and use a lot. I'm just shooting better with the SKB. Thanks very much for the feed back!!!!
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  • bobski
    but...no mention was mad if they were fixed chokes?[?]

    former air operations officer SEAL Delivery Vehicle Team 2. former navy skeet team, former navy rifle/pistol team member. co-owner skeetmaster tubes inc.. owner/operator professional shooting instruction. NRA certified instructor.
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  • Tailgunner1954
    Bobski
    That was a Ass-u-me-tion on my part, and maybe a my-bad.

    Whittemore
    Some guys like a mag full of lead, I still prefer one round to the head.
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  • nord
    First, 40 yds. for light shot means a pretty fair sized pattern.

    You fail to mention whether the upper tube appears to shoot low or the lower tube appears to shoot high at that range. (I'll bet it's so.) Here's what I suspect:

    Each gun in question will be designed to have a convergence point somewhere forward of the muzzles. My guess is that it's at about 25 yds. on a field gun. Past that point the lower tube would appear to shoot high and the upper tube would appear low. This is ideal for upland game as targets usually fall within 100' of the shooter.

    Specialty guns are likely to have their convergence adjusted to meet the intended task. This is something I'd have checked with the manufacturer. I'd guess that your Ruger and your Winnie are spot on for their intended purpose.

    One thing I think should be mentioned... Had you patterned on a moving target, I believe your total spread would be more of an average between the loads instead of the extreme noted by firing at a still target.

    Neither Ruger nor Winchester make junk. I'll say the same about your SKB, but I don't think it's by any means a better gun. I'll bet there's a certain method behind what you're seeing.

    Nord
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  • dannej
    bobski, they all have screw-in chokes..

    Nord, You may be onto something here. The lower tube shoots high on both the Ruger and the Winchester. Both have shorter barrels then the SKB which has a 30 inch barrel, which may indicate a field gun on the two and a duck or trap gun on the SKB. Also of note as to patterning, in all three guns I shot slugs from the bench at forty yards to check grouping. I used the IC choke in each barrel to shoot a five shot group for all six barrels. That is how I got the specific inches measurement difference in group center. The patterning also showed a noticable difference in group center which was consistant with the slug groups.

    I have had the Win. for years and average about 40% on birds. I used the SKB this year and averaged a bit over 50%, but it also has a rib and bead that is easier to pickup quickly. The Win. is a 20 ga. three inch magnum and the SKB is a 12. I'll try the Ruger on my next outing after Thanksgiving. It has the English stock and twenty six inch barrels and I love the feel of it and it should be quick on chukars.

    Thanks so much for the input!!
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