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Back bored barrels??

Discussion in 'Shooting Related Threads' started by Chadshot, Nov 11, 2009.

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  1. Chadshot

    Chadshot Member

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    Looking at an SKB 505, they don't have back bored barrels, I really like how it shoots though. What is the advantage or disadvantage of this??
     
  2. Jennifer

    Jennifer Member

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    Well I'm certainly no expert but I was just reading about it which is why I asked the question about my Beretta on another thread. The book stated that when the shot travels down the barrel to the choke, the pellets have to either reposition themselves or deform in order to cram through the choke constriction. Having a larger diameter bore, and hence a larger diameter choke, would cause less pellet deformation and consequently better patterns than a tighter bore and choke would. This would seem to be more critical for the longer yardage shooters who are using tighter constrictions such as the .035" full choke, compared to the .009" constriction of improved cylinder for a shorter yardage shotgunner. Jennifer
     
  3. Jennifer

    Jennifer Member

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    Oh I also forgot to add that backbored bbls are supposed to cause less perceived recoil too... Jennifer
     
  4. zzt

    zzt Well-Known Member

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    The best patterning barrels I have ever owned were a Superposed O/U with .722" bores. Next best is an Allor tuned O/U and Unsingle. They have .740" and .745" bores, respectively. I've owned Wilkinson .740" bored barrels and stock Beretta @.0732 and stock Perazzi @ .734".

    Admittedly, this is a very small sample, but I can find no correlation between bore diameter and PE, except to say that the Superposed barrels threw patterns to die for. So do the Allor barrels. Go figure.
     
  5. redhawk44

    redhawk44 Member

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    I think that better patterns are the result of better load development rather than the internal dimensions of the barrel.

    If you want good patterns, tinker with the powder/primer/wads and powder charge elements of the load until you get the results you require and then stick with it.

    While I would agree that a 12 ga. 1 oz load will USUALLY produce a better more evenly distributed pattern than the 1 oz 20 ga. loads, that is a far cry from a mere 10 or 15 thousandths difference in the so-called overbored barrels.

    Overbored barrels, long forcing cones, porting and engraving are designed to sell tooling and shotguns and not necessarily to produce better results.

    On the other hand, these things don't hurt anything, so if you THINK it will help you it probably will.
     
  6. W.P.T.

    W.P.T. TS Member

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    redhawk44,

    Thats all well and good for those that reload but what about those that don't ... There was a time not all that long ago that people would shoot reloads all year long and then go to the Grand American and have to shoot new shells with little or no data about how they patterned in their guns ... WPT ... (YAC) ...
     
  7. redhawk44

    redhawk44 Member

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    WPT....If one does not handload the only thing to do would be to try different brands of ammunition, much like smallbore rifle shooters do.

    Also my post above was just my opinion as are all my posts. I have little scientific data to back up those opinions.

    Of course, there is not much science to back up the idea of longer forcing cones reducing recoil, but I happen to know more than a few who would testify that it does.

    Between the power of suggestion and the subjectivity of the thing......well nuff said. ;-)
     
  8. miketmx

    miketmx Well-Known Member

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    Note the link above for an opinion from the Technoid. My TMX has a factory bore of .728 and my MX3 Single barrel was tricked up with a bore of .735 and both guns shoot very efficient patterns.
     
  9. Jennifer

    Jennifer Member

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    That's a pretty interesting article. I had forcing cones lengthened on an 80s-era BT99 and did notice reduced perceived recoil. After reading that article, backboring would seem to be another gimmick or placebo.
     
  10. 22hornet

    22hornet Well-Known Member

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    I'd just shoot that 505 and not worry about it. They are good, workhorse shotguns.
     
  11. redhawk44

    redhawk44 Member

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    Perceived recoil is difficult to quantify.

    Sometimes a slight difference in gun mount will soften recoil. If I mount the gun a little too far outside the pocket, the recoil seems to be worse. Also the length of the stock will affect the perceived recoil, short stocks being a little more punishing than longer stocks.

    Lengthening the forcing cone might marginally reduce the pressure at the beginning of the curve, but since the pressure in any event reaches the top of the curve in 1 or 2 thousandths of a second, I am unconvinced that this would make a measurable difference in the recoil.

    It is not pressure that causes recoil, if it was, the .223 Remington would kick harder than a 12 ga shotgun....it doesn't
     
  12. warren

    warren Member

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    I own a Browning XT that is back bored and a Rem. 870 that is not and if the recoil is perceived I must say it is a very strong perception. I also own a .223 but it is gas operated and that reduces the recoil I'm told. It hardly recoils at all my wife who has had open heart surgery enjoys shooting it.

    warren
     
  13. Jawhawker

    Jawhawker TS Member

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    The real story is that and H&R Topper may throw just as efficient patterns as a well tuned aftermarket barrel. Until one runs tests its all assuption. No absolutes in life unfortunately.

    PS. I hope you can keep that gun runnen!
     
  14. Chadshot

    Chadshot Member

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    Thanks for the info, I did shoot a friends 505, hard for me to say it has more recoil than my other shotguns. Anybody have any good or bad about SKB 505. The one I shot was a friend of mines skeet gun, he has not had any problems with it.
    Chad
     
  15. phirel

    phirel TS Member

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    redhawk44- Peak chamber pressure is achieved between 3 to 6 ten thousands of a second, not 1 to 2 thousands of a second.

    Backboring and lengthening the forcing cones could reduce recoil if these treatments reduced the velocity of the shot charge. Slight changes in gun mount and the force the gun is held by the hands will certainly affect perceived recoil. And our mind will affect perceived recoil. If one firmly believes that a certain shell kicks less, that is what they will feel. I feel my handicap shells kicking more when I am shooting a poor score. When I am shooting well, they seem to have no recoil. Is it possible that the shells in one box know what I shot on the previous field?

    Also, on popular brand of discount shells, labeled as 1 1/8 shot and 1200 ft/sec will actually kick less than other brands labeled the same. The reason is that the velocity is actually between 1125-1150 ft/sec.

    Pat Ireland
     
  16. PerazziBigBore

    PerazziBigBore TS Member

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    Patterns.. long range... Nothing has ever equaled my Bernardelli hammergun SXS .722 bore .055 chokes.. or .721 bore.. .042 chokes..
     
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