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Reloading questions?

Discussion in 'Uncategorized Threads' started by Shooting Jack, Dec 9, 2007.

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  1. Shooting Jack

    Shooting Jack Active Member

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    What is the relationship of Muzzle Velocity and Chamber pressure? I have reloaded skeet shells for years but those same loads do not work well for me shooting trap. I have found that I can take factory loads and score much higher than with the skeet reloads. How do you differientate between powders, IE. Hot, slow, heavy, light? I have a number of books but don't find the answers to these questions. I want to have a good load for trap and have the following powders. 700X, Unique, Red Dot, Clays, International. Thanks for your help. Jackie B.
     
  2. Capt. Morgan

    Capt. Morgan TS Member

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    Using a single powder and a given combination of components, higher muzzle velocities require more powder which generates higher chamber pressures. There is a limit to the pressure you want to create...11,800 PSI... for a 12 ga. gun. The velocity that that amount of powder will produce at that pressure is the maximum velocity that that powder/wad/primer/hull combination can safely produce.

    Changing to the same charge weight of a different powder may produce lower pressures but the same velocity so you could use more powder and generate more velocity before the pressure becomes excessive (Be careful; it may also produce higher pressures; read the data carefully!). Keep in mind that the velocity and pressure a given weight of a given powder produces are a function of the combination of shot weight, wad, hull and primer and not just the powder alone. Coming upon a "good load for trap" is largely a matter of experimentation using published data to find what works best for you and your gun. That's why powder is sold in small bottles.

    Above is a link to Hodgdon's powder burn rate chart, one of several versions on the internet. Take them with a grain of salt because you will find differences among them, especially among the first 40 or so powders listed. Of the powders you mentioned, Clays, Red Dot and 700-X are very similar in published burn rate while the others are listed a "slower" which means that equal quantites of a slow-burning powder will produce less pressure than a faster burning one given the same components.

    Morgan
     
  3. Setterman

    Setterman Well-Known Member

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    The only relationship is that when you add more powder, you increase chamber pressure. I have found that most high pressure (Fast burning) powders like Red Dot, work best on shorter yardages. Green Dot and International, slow burning powders, work best to hold a tight pattern core, and are good for long yardage shooting. Every gun is unto itself and shoots some loads good, some loads not so good, or so it seams anyway. Chamber pressure is also affected by the wad and primer. Keeping a "consistant" load is more important than speed. Being mentally confident in your shell's performance is even more important. Personally, I prefer to not exceed 10,000 psi in any reload. Keep it safe.
     
  4. tomk2

    tomk2 Member

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    For a given powder, wad, hull, and load, as chamber pressure rises so does velocity. However, the relationship is not linear. If you use recipes that are not pressure tested, it is possible to make what you think is a small change in the recipe that in fact creates a large change in pressure. Thus, never combine components that do not have pressure tests specific to that combination.

    Lots of people use Clays powder, ounce or ounce and an eighth of 7.5 or 8 shot, at a velocity between 1145 and 1300 fps for trap. My pet loads are the 1145 and 1200 fps velocity in 1.125 ounces, but I do frequently use 1 ounce at 1200 fps of 8's for the first shot of doubles.

    These recipes are readily found in reloading manuals and on the hodgdon website.
     
  5. Phil E

    Phil E TS Member

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    Go to the Hodgdon site link above, click on "shotshell" and "data" and you'll find the data you need, for Hodgdon Clays. It'll work fine for you. Pick a middle-range 1-oz load there, with the hull & wad & primer you have. Phil E
     
  6. ink ball

    ink ball Member

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    Setterman's advice is sound, and I agree with his recommendation to keep pressure below 10,000 psi. Lower pressure tends to give less felt recoil, as well.
    Generally speaking, heavier loads and faster velocities require slower burning poweders to keep the pressure within safe limits
    My favorite trap load (that also works great for skeet) is 700X with 1 oz of 7.5's shot at 1200 fps. It has patterned superbly through several different guns, and have found it works great for trap at all yardages. I load STS hulls, but it works well in AA's, too. See Hodgdon's web site for loading data.

    Gary
     
  7. alfermann66

    alfermann66 Member

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    Jackie B, in answer to your first question.....there is no relationship. Select the ejecta weight you desire, the speed you want, the wad, primer and hull you intend to use, then select a powder and charge weight that provides that performance and has a chamber pressure between 8000 and 10,000psi. Your International or Unique will suffice for a 1 1/8 oz. 1250fps handicap load.

    Buz
     
  8. Capt. Morgan

    Capt. Morgan TS Member

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    <I>"Setterman's advice is sound, and I agree with his recommendation to keep pressure below 10,000 psi."</i>

    There is no good reason to keep chamber pressures below 10,000 PSI unless you (1) don't check the powder drops with a scale or (2) don't trust the scale you have. Most powders require a pressure of 7500 PSI or higher to assure reliable and consistent ignition but there is no reason to give up 1800 PSI of usable pressure from a powder if you think you need it.

    <I>"Lower pressure tends to give less felt recoil, as well."</I>

    Recoil is simply a function of the weight of the shot and wad accelerating to a given speed against a gun of a specific weight. Here is a relevant quote from the Hodgdon web site FAQ:

    "Q. Does chamber pressure have any effect on recoil?

    A. Chamber pressure does not have anything to do with recoil. Chamber pressure is equal in all directions like the atmosphere inside a balloon. It is not a measure of thrust. If you are shooting a modern firearm, chamber pressure really has no meaning. If you are shooting an old iron framed shotgun or an English/European shotgun with low proof, our chamber pressure data will serve to assist you in picking an appropriate load.

    The only real way to lessen recoil is to lower velocities, or lessen the shot charge, or both."

    Morgan
     
  9. ink ball

    ink ball Member

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    Yes, Morgan there are reasons to keep pressure under 10,000 PSI, one of which is that lower pressures tend to result in less deformed shot. In some cases, it is difficult to keep pressures low especially in the small gauges. However, with 12 gauge target loads, it is pretty easy to do. I have also observed that higher pressure loads, in many cases, don't pattern as well as lower pressure loads. As long as you are making a reload, why not make as good a reload as you can? But you are correct, going too low on pressure is not good, either.

    Also, read my post regarding recoil a little closer. I said "Lower pressure tends to give less felt recoil..." FELT Recoil, not actual recoil. Lower pressure peaks and slower pressure peaks will results in less felt recoil.

    Gary
     
  10. hmb

    hmb Well-Known Member

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    Chamber pressure doesn't have anything to do with recoil. You must be kidding. If you have no pressure you have no recoil, if you have alot of pressure you have recoil. That sounds like the beginning of a lasting relationship to me. HMB
     
  11. ink ball

    ink ball Member

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    HMB

    I dont think this is the right environment to give you a Physics lesson, so I won't! Happy Holidays!

    Gary
     
  12. Shooting Jack

    Shooting Jack Active Member

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    In 12 gauge loads I used for skeet, one of which was AA hulls, 15.3 grains of 700X, Fiochi 616 Primers, CB 0178-12 wads and 7/8 of No. 9 shot and really works great. But it just doesn't seem to have the oomph for trap and I have been averaging 5 birds less when using this load. I can pick up a box of the cheap 1 oz loads from Wally world or Rio's or Estates and shoot well with them. The store bought shells definitely kick more but do a better job of breaking the birds. To say I'm lost is an understatement. When I started shooting trap I had about thirty flats of ammo I was using and recently changed over to reloads and a different gun. With factory ammo I get good results with the gun though. Jackie B.
     
  13. Capt. Morgan

    Capt. Morgan TS Member

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    If I had to guess, I'd say that 7/8oz of #9 shot might have something to do with your lower scores. There isn't a lot of energy in #9 shot at 40+ yards. And you haven't indicated what constriction you're shooting it through for trap.

    Morgan
     
  14. Shooting Jack

    Shooting Jack Active Member

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    I have tried Briley Full and Modified with about the same result.
     
  15. Capt. Morgan

    Capt. Morgan TS Member

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    Try the same loads you've been loading with #7.5 or #8 shot and see if there is a difference. These loads will contain less shot but each pellet will retain more energy downrange.

    Morgan
     
  16. phirel

    phirel TS Member

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    Capt. Morgan- How much energy is required to break a target?

    Pat Ireland
     
  17. timb99

    timb99 Well-Known Member

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    If chamber pressure related to recoil, then I guess my .410 loads at 11,000 psi should recoil more than my 12 gauge loads at 9,500 psi?
     
  18. Setterman

    Setterman Well-Known Member

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    When I said I prefer to keep my loads under 10,000 psi, it was not because of recoil. I'm sure Neil and Pat know why this is a good practice. Some powders like Red Dot and Super Handicap are exempt from that statement.
     
  19. hmb

    hmb Well-Known Member

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    410s can have alot of recoil, it just depends on the gun you shoot them in. The other day I shot a revolver chambered for 410 shot gun shells. Believe me, there was alot of recoil. HMB
     
  20. timb99

    timb99 Well-Known Member

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    HMB

    Now YOU must be kidding.

    I shoot .410 with sub-gauge tubes in my 12 gauge O/U.

    The recoil difference is drastic. When shooting .410 shells in it, if I didn't hear a bang and actually see the target break, I would be hard pressed to tell you if the gun went off. You can barely feel it.

    Chamber pressure is not related to recoil, either felt or real.

    Its muzzle velocity and ejecta mass!
     
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