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Technical Barrel Question

Discussion in 'Uncategorized Threads' started by timb99, Feb 20, 2007.

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  1. timb99

    timb99 Well-Known Member

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    It is the inside diameter of the barrel, between the end of the forcing cone and the beginning of the choke, in fractions of an inch (0.740 inches.)

    The "standard" 12 gauge bore is 0.729 inches.
     
  2. timb99

    timb99 Well-Known Member

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    First, a history lesson.

    The term "12 gauge" corresponds to taking a pound of pure lead, dividing it into 12 equal pieces (1/12th of a pound each), and making a sphere from that 1/12th pound piece. The diameter of the sphere defines the inside (bore) diameter of a 12 gauge gun.

    The term "overbored" when used in reference to shotguns, means that the bore diameter is larger than the standard 0.729 inches. In the case of a 0.740 inch diameter bore, this is still a 12 gauge gun using 12 gauge ammo, but the bore diameter is larger than standard. There is some belief, and indeed some proof, that larger bore diameters make for better shot patterns down range.

    Does that answer your question?
     
  3. Neil Winston

    Neil Winston Well-Known Member

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    Proof, timb99? Where? When?

    Neil
     
  4. Neil Winston

    Neil Winston Well-Known Member

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    Zar, I don't know if it's true. I've tested many and never seen it, but perhaps someone _has_ proven it. I'm just asking for the reference, that's all.

    Neil
     
  5. Prescott Gene

    Prescott Gene Member

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    For some reason, I seem to recall that Stan Baker did some research on the subject but that was 20 years ago. He developed the Baker Big Bore which took off like a short fueled missle.

    Gene
     
  6. LazerRed

    LazerRed TS Member

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    http://science.howstuffworks.com/shotgun3.htm
     
  7. timb99

    timb99 Well-Known Member

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    Neil,

    My mistake.

    I thought it was YOU who had posted once that your overbored barrel had slightly better patterns than your standard barrel.

    If my memory is wrong, my apologies.

    Tim
     
  8. whiz white

    whiz white Strong Supporter of Trapshooting Banned

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    Question to ask is: "Why a bigger bore?"

    I know, but not sure all do...

    WW
     
  9. 682LINY

    682LINY Member

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    Don't you all know bigger is always better,,,or so I've been told,,,and I wont say by who,,,,but she was cute
     
  10. rollnblock

    rollnblock Member

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    Whiz: to answer your question. .729 barrels were fine with paper (cardboard) backed shot. the advent of plastic wads is why the .740 barrels. the paper backed shells had no wad fingers around the shot. just the paper pushing the shot down the barrel. now the plastics have fingers around the shot while traveling down the barrel. about 5-6 thousandth per side finger. so ther is the 10-12 thousandths differanc in barrel diameters.

    Dave
     
  11. TOOT

    TOOT TS Member

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    Sure would be interesting, if one day one of the the folks that make their living in part on back boring (and tuning) barrels...would comment on the subject.

    I suppose they are at risk of shooting themselves in the foot but they have no problem promoting the techniquies they apply in their adversiting.

    BTW....Beretta has their share of Optima overbore barrels also.....and many other manufacturers. I realize they may just be giving us what we want or think we need instead of any sound engineering reasoning.
     
  12. hmb

    hmb Well-Known Member

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    Having the correct POI is far more important than bore diameter. HMB
     
  13. Neil Winston

    Neil Winston Well-Known Member

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    When I asked above if anyone has proven it, I was hoping for an example.

    ...and I don't see anything yet. Mike, the "square" argument would be a candidate explanation of an observed effect. But it's not evidence.

    And so with the whole rest of what you've written. Stan Baker never published his results beyond a two issue puff-piece written by Don Zutz in Shooting Trap. And there are plenty still out in the field, in fact I hope to take Jeff up on his offer this spring. But so far, I've seen no proof. If you have one, why not pattern it and post the results, with photos, here?

    I personally think you should give Dr. Jones more credit than you seem to. We do know, for example, that he's patterned lots of guns and published the results, as have I. We shoot real patterns and have nothing to sell, and we don't get the kind of results we were told -by people like you - that we would get. Though several of my tests were lost in the crash, there's still plenty here searchable by Winston which compare standard and overbored guns.

    My Bowen (0.740)shoots well, as does Perazzi RP, an untouched Ithaca import. My factory overbore Perazzi doesn't fare as well, and the same goes for a couple of modified Perazzis as well. My best so far was an 870 whose bore was about 0.734 as I remember.

    Here's what I mean by "well, best," and so on. Andrew and I have a couple of standards for "good." I like number of pellets on 30 inches and the probability of a hit in various areas as calculated by his program.

    In restricting myself to this kind of analysis, which is backed up by ten actual patterns which is, at base, the "evidence" I find myself never using "perfection," "outproduce," or any such slippery, undefined generalizations.

    If particular interest was your statement:

    " I guess what I'm saying here.. is the predictiability of a larger bore barrel.. properly tuned.. can be measured.. "


    Now there's a possible definition. Does this mean that in shooting 10 patterns there will be a smaller spread between the highest and lowest percentage with a larger bore? I've never found such an effect. If anything, it's mostly the other way.

    And then Mike, you go completely Shotgun sports on us! "He'll instantly understand his barrels performance on a moving target" which is what people say when they have no data.

    As to your final challenge, shoot patterns, I've done it. Tons of them, and posted them here besides. I didn't get the results you predict. I suggest as simple trip to a pattern board for you just as you do for Dr. Jones. Shoot'em, photo'em, and prove it.

    Neil
     
  14. CharlesR1100

    CharlesR1100 TS Member

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    Glad I do not have a dog in this fight! Also glad I do not smoke. But...
    it simply begs belief that a top shooter really would only want to hit one side of a target over another. With "big money" on the table? Not creditable.
     
  15. Neil Winston

    Neil Winston Well-Known Member

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    Interesting question there, Mike. Say the target were moving at the same speed as the shot (crossing target, of course.) Would it make any difference, and if so, better or worse?

    Neil
     
  16. Neil Winston

    Neil Winston Well-Known Member

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    Mike, Bob Brister did experiment with moving targets, that is, painted targets on paper driven by his wife. He was interested in duck-pellet sized shot, and his main point was that soft lead pellets, unbuffered, produced long shot strings and that short shot stings were always better.

    What most missed was a paragraph in another place in the book, not where you would expect it at all, in which he loaded some shells with hard 7 1/2 shot from trap loads, and on a crossing target at 40 yards, said that the pattern was perfectly round and gave no evidence of stinging whatever. I don't have the book where with me in Texas, but someone can look it up and confirm it.

    I've long objected to the TS.com habit of, as I call it, "going somewhere else." My early challenge was straightforward. If big-bore patterns are better, then big-bore patterns (and nothing else) will prove it. But now you've veered off to shot stringing. We aren't talking shot stinging, particularly since Brister told us it didn't show up, we are talking patterns. If they are not different (or better) then saying "Well, I know they break targets better" simply won't cut it. The patterns, once again, will tell the story and so far as I know, no one has ever produced anything we should pay attention to.

    Just as you have shot with good shots, for the last two decades my Grand squad has had at least two All-Americans, sometimes as many as four. Zookie a couple of times credited his NCP Beretta with his fine doubles shooting, but aside from that in - how many? 20 x 20 x 5 x 100 = 200,000 targets - some by Grand winners when I was shooting with them, no one has ever mentioned bore diameter. They've changed guns to be sure, some this way, some that, but the specific subject of bore diameter has never been mentioned. This indicates to me that they don't think it's worth thinking about.

    But you've given me a research project. I'll post some data here, under the title "Tell standard from overbore" and I'll let you and others separate 15 patterns into two groups: standard and overbore. Then I'll tell you how you scored.

    Neil
     
  17. phirel

    phirel TS Member

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    Neil - If you do that, I will guess all standard and I think I will get about 7 of them right.

    Pat Ireland
     
  18. Neil Winston

    Neil Winston Well-Known Member

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    ...which leads me to think about a way to make the test more revealing, Pat.

    Say I take patterns all from the same gun, tell people half are from an overbore, and see what they pick. I'd like to predict they'd say "this good one here, this not-as-good-one over there" but I'd rather wager that they, and in fact you, after giving serious effort to either problem, the legit one or the deceptive one, will say "I've no idea. I can't even remember what I thought I was going to be looking for. These things are _all_ different (when I count pellets), or, equally true, all the same (when I eyeball them)."

    Neil
     
  19. Johnny

    Johnny Well-Known Member

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  20. Chuckie

    Chuckie Member

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    Here is another twist. What is the effect of bore diameter in relation to very cold shooting conditions? Why is it that some factory loads, and some reloads
    fail to perform in over bored barrels, during harsh cold weather. I am speaking
    only of target not hunting loads.
     
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