Pas que ça vaut pas cher, mais si tu comprend bien l'anglais, lis ce qui suit:
This is info from Nitro Shell Company which is arguably the best turkey shell out there. They do more real life testing than any other folks I know. I've never heard of anyone not having great results when choke/load recomendations are used. Today the modern turkey guns are more advanced than they once were. New technology has wiped the old theory (big shot, open choke), out of existence. Nitro Company's research and development department has done extensive testing on how to get the maximum performance out of all guns. Here are our findings that we feel will give the turkey hunter the edge on the elusive gobbler. The modern turkey hunter sacrifices pattern performance and velocity for maneuverability of a short 21" barrel. A gun with a 26" barrel will give you higher velocity and better patterns. For every inch up to 26", you gain 7 1/2 to 15 feet per second in velocity, depending upon the gun. A 26" barrel will give you 10 to 15 percent better patterns than a short barrel with the same choke constriction.The early turkey guns were furnished with fixed chokes and did not have the option of screw in chokes as we have today. Fixed chokes and sleeves are things of the past, since advanced technology has made these obsolete. Screw in chokes give the turkey hunters many options of diameter size constrictions. What works in one gun might not work in another, it is also true to say that what works in one barrel, might not work in another. In the past, the theory claimed open chokes for big shot. Choke constriction does not always work that way. If you have access to many different chokes and want to shoot #4 shot, they might shoot the best out of a real tight choke or they might shoot best out of a slightly open turkey choke. The only way to find what choke works best with your shot size, is through testing. As you can see, there are many advantages of having a screw in choke. Due to the harmonics (vibration) in the barrel, you do not know if your barrel is going to like a ported or non-ported choke. Whichever one works to give you the maximum pattern, is the one for you. Ported chokes are highly recommended if they work in your barrel. Modern choke tubes are also ported as a wad stripper, they keep the jump of the muzzle down, and reduce recoil. The bore (inside) of the barrel is the most important part of your shotgun. We recommend a highly polished bore without lengthening the forcing cone. Our goal in a pattern is center pattern and center density. We are interested in a 10" - 12" circle with quarter pie sections because of the way a turkey’s head is constantly moving. A 30" circle with percentages is used for flying birds, such as duck hunting. For a spring turkey hunter, this is a thing of the past. To gain center density, you would first have to start with an ultra clean barrel. This means no oil, water, plastic fouling, powder fouling or lead fouling in the barrel. To start, put some solvent that will remove all plastic and lead fouling in the barrel. Put the solvent on a patch over a bore brush and get as much fouling out as possible. After that, put some solvent on a clean patch and just run it down the barrel. Leave it for about 30 minutes or more and then put more solvent on a patch and put it over a bore brush and scrub clean. Keep using as many patches as necessary until the patch comes out clean. When testing, you should always run a dry patch over a bore brush attached to a cleaning rod down the barrel between every shot to give the shells that you are testing a fair chance. By not doing this, you will lose 10 to 15 percent or more of your center core pattern. The smoother the bore, which will have less interference for the shot and wad, the better your center pattern will be. This is why we highly recommend polishing the barrel. Weather, such as wind, humidity, dew point, rain, and dense air will open your center pattern. The ideal condition is no wind, 60 degrees temperature, with no humidity or very low dew point. This is when all your testing should be done. After finding the load and shot size that gives you the ultimate performance while testing in ideal conditions, you should also test in all different weather conditions so that you know what your pattern is doing. Such as in the rain, high humidity or high dew point. There are a wide range of shot sizes and types of shot for the turkey hunter to select from today. Such as 2, 4, 5, 6, 7.5, 2x4x7.5, 4x5, 5x7.5, 4x5x7.5, and many others that are available on the market today, as well as the choice of nickel or copper plated shot. Nickel shot penetrates deeper because it is harder and stays more round at longer distances. Therefore, nickel shot penetrates deeper because it will not pull feathers. Copper deforms more and loses its pattern at longer range. The only way to tell which shot your gun likes best is through testing. The muzzle velocity of the ammunition you decide to use, must be at least 1,100 fps (feet per second) to kill a turkey at 40 yards with a small shot size. To penetrate the vitals of a turkey head and neck, the ammunition must hit with at least 1.8 foot pounds of energy. It is very important to know the length of the test barrels used to test velocities of the ammunition you select. If ammunition velocity is tested out of a 30" barrel (as most manufacturers use), you would be very disappointed to know that you will not be getting their advertised velocity from a 21" barrel. If you have access to a chronograph, which measure feet per second velocities, you should test your ammunition to make sure you are shooting over 1,100 fps. Nitro Company tests all ammunition out of 21" & 24" test barrels (depending on the gauge of the gun) so that you will be getting actual velocities. We also temperature rate our shells for the maximum performance you will get at those temperatures. Cold weather can hinder patterns drastically if loads are not chosen carefully and tested in colder weather conditions. Another important factor of your shotgun is your sights. Make sure you shoot your gun and that it is shooting point of aim. If your shotgun is shooting off, a set of rifle sights or scope could solve the problem, this way you can adjust it to the point of aim. Many birds are missed because the hunter does not see where his point of impact of the shotgun is shooting. Another thing is that you should make sure that your gun fits you, if you have to shorten or lengthen the stock, then do so. A shotgun should pull up with no interference from your arm, clothing, etc. Another reason turkeys are missed is because when you are shooting and patterning the gun on the range you are holding it tight and into your shoulder. When you call in a gobbler, your relaxed and you hold the gun loose. This will make you shoot high and possibly shoot over your gobbler. For more info and free catalog, contact Nitro Company, 7560 Newkirk Road, Mountain Grove, MO 65711 * 417-746-4600.
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