Some interesting facts...

Discussion in 'Firearms & Ammunition' started by Norma-USA, May 20, 2014.

  1. Norma-USA

    Norma-USA SPONSOR AH Senior Member

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    1. Where can I get a Norma catalogue?
    Your nearest shooting supplier will generally stock our latest catalogue. If not, you can check out our website to download a copy at http://www.norma.cc/en/About-Norma1/Catalog-and-Downloads/.


    2. How long can you keep ammunition for?
    Do not use ammunition that is any older than 15 years.


    3. How should I store my ammunition/powder?
    We recommend in a cool place at a constant temperature (12-15°C) and approx. 50 per cent relative humidity. The chemicals in the powder slowly start to decompose after about 20 years. If you store the powder at a high or fluctuating temperature, this process starts earlier.


    4. Where can I find further information on ballistics?
    There is a ballistics calculator on the Norma website where you can see the parameters for various bullets, such as velocity, range, etc. Pure ballistics data is to be found in most manuals, such as the Norma reloading manual.


    5. What is meant by the ballistic coefficient?
    The ballistic coefficient (BC) of a body is a measure of its ability to overcome air resistance in flight. This coefficient is a relative value compared to a standard bullet with a BC of 1.0.


    6. What effect does a short or long barrel have on velocity?
    A long barrel results in a higher velocity, as the propellant pressure is significantly higher than the friction in the barrel. The velocity generally increases by 2-3 m/s per cm.


    7. What is gunpowder?
    Gunpowder is made of cellulose, which is obtained from the seed fibres of the cotton plant. Nitration (treatment with a mixture of nitric and sulphuric acid) adds oxygen to the cellulose. To ensure that the powder burns at the right rate, the powder grains that are of different sizes are treated with various chemicals (see the Norma manual, p. 88-121).


    8. Are magnum primers required for large cartridges?
    Fast ignition with an adequate amount of powder is important. The more powder used and the more surface treated (sluggish), the more difficult it is to ignite. A magnum primer is required for loads containing more than about 5 g powder, but can also be used for smaller loads.


    9. How many shots can you fire with a barrel?
    Firing bullets only wears the barrel to a very slight extent. What is decisive is the amount of powder relative to the barrel diameter. You can fire 500 to 1,000 shots with a .7 Rem Mag, depending on your style, and five to six times as often with a .308 Win before the precision slowly starts to be affected. Shooting when the barrel is still hot naturally causes much greater wear than firing shots at longer intervals.


    10. Where can I obtain information on reloading?
    Our reloading manual contains simple instructions and loading data. If you wish to find out more about the technology and equipment, various reference books (usually in English) are available on the internet. In addition, shooting magazines run articles on the subject from time to time.


    11. What is meant by twist rate?
    The twist rate is often stated in inches (1 inch = 25.4 mm) and indicates the distance a bullet must travel down the bore to complete one full revolution around its long axis. Most calibres have a twist rate of one turn in 8 to 16 inches.


    12. Why can't you use all bullet sizes in a particular gun?
    Short (light) projectiles require less rifling in the barrel than long ones to achieve gyroscopic stability. Every bullet has a specified twist rate that is designed for certain projectile weights. Problems occur when you use extremely long (heavy) bullets and the twist rate is not high enough to stabilise the projectile. Example: the .308 Win has a twist rate of 12 inches. All bullets up to around 12 g are suitable. Heavier projectiles may result in an oval bullet path and reduce accuracy. Lighter projectiles receive more spin than they actually need, which is however practically without significance.


    13. Why does muzzle flash sometimes occur?
    A normal bullet releases about three litres of gas. When it reacts with the oxygen in the ambient air, it can ignite and form a flame, which is visible especially in the dusk.


    14. What should you take into account when shooting at low temperatures?
    Test fire the gun at the temperatures to be expected on your shoot. Leave the gun to cool down for about an hour. You can either keep the ammunition in a jacket pocket or at the same temperature as the gun.


    15. What is the difference between rimfire ignition and centrefire ignition?
    Rimfire cartridges have the priming compound in the rim of the case, such as in a .22 LR. In centrefire cartridges on the other hand the firing pin strikes the primer at the centre of the case to ignite it with the priming compound located between the brass cup and the anvil.


    16. Why are cartridge cases made of brass?
    The case keeps the powder, projectile and primer together and ensures the tightness on the backside. It has to withstand the pressure and be capable of being removed after the shot. Brass containing 70-72% copper and the remainder zinc meets these requirements. Cases have also been made of steel, for example, but are not corrosion resistant and tool wear is greater. Softer materials such as aluminium are slightly less strong and may oxidise at the surface. Brass is therefore a very good compromise.


    17. Where can I buy equipment for reloading?
    Larger shooting suppliers usually carry a good range of equipment. The choice is greater on the internet, but you have to know exactly what you need. It is better to familiarise yourself with the procedure for reloading and the equipment required first. If possible, get a friend to show you the individual steps.


    18. How much energy is required to ignite a primer?
    This question is not very easy to answer, as it depends very much on how fast the firing pin strikes it. According to military specifications, dropping a steel ball from a given height must ignite virtually all of the primers. There are also rules where the drop height is low and none of the primers should ignite.


    19. Does Norma have instructions for reloading?
    Only in the form of the reloading manual.


    20. Can I use match ammunition for hunting?
    According to hunting regulations, a hunting projectile must have a point that enables expansion or mushrooming. Match ammunition is not therefore allowed. In some countries there are not any regulations with the result that both types are used. A bullet that does not expand at the front quickly becomes unstable and releases energy. When a bullet comes into contact with a strong bone, it does not penetrate to the vital organs, which means it only wounds. A good shot also usually results in considerable tissue damage.


    21. How loud is a shot?
    Sound level is measured in decibels (dB). The decibel scale is not linear, i.e. 100 dB is not twice as loud as 50 dB. An increase of 3 dB means a doubling of the loudness. As a result, 100 dB is around 17 times as loud as 50 dB.

    Different measuring methods produce different results. The figures below are based on measurements carried out in the USA.

    .22 LR from a handgun 158 dB
    .22 LR from a rifle 139 dB
    9 mm from a handgun 160 dB
    .223 Rem from a rifle 166 dB
    The level causing permanent damage to the human ear is about 120 dB, which is why you should always wear hearing protection.


    22. Where can I get ammunition for old guns?
    Shooting magazines frequently have advertisements. Make sure however that the ammunition bears the same designation as the gun. Using old cases can be dangerous, as brass becomes brittle after being stored for long periods.


    23. Can you use .300 Win, .300 Weatherby and .300 Ultra Mag cartridges in one and the same gun?
    No, under no circumstances. Every cartridge has its own designation. In this case, the number 300 stands for the calibre, i.e. 0.3 inches = 7.62 mm. The nomenclature used by the Swedish Environmental Protection Agency can be confusing at times, as it gives cartridges as calibre x case length. There are several cartridges with the same designation, which does not lead to clear classification.


    24. Where can I find out about Norma's company history?
    Our reloading manual (2004) also includes about 20 pages with details of our company history.


    25. Is there more detailed information on the new standard calibres .300, .338 and .375 Norma Mag?
    When producing the current catalogue, we mentioned these three cartridges briefly as being planned but they were still undergoing development. We assumed that the .338 and .300 would be suitable both as long distance and hunting cartridges. Both are now available as cases. The .375 is still at the development stage.


    26. What is meant by breaking in a gun?
    The term applies to firing initial shots with a new gun as recommended or after replacing the barrel. Breaking in involves firing a shot and cleaning the barrel, then firing another shot and cleaning the barrel again. You have to repeat the process until there is no more tombac residue left in the barrel. To check, stuff a cleaning cloth 2 cm into the muzzle. Afterwards you can fire three shots and then five shots several times, always cleaning the barrel between the rounds of shots. If the barrel is of high quality, fewer shots (about 10 to 20) are normally required. Thin jacket deposits near the muzzle do not affect performance.


    27. How should I clean my gun?
    There are many procedures you can follow, but we have described two common ones below.

    Soak a cleaning cloth with solvent or oil and pull it through the barrel. Pour solvent onto a suitable bronze brush. There are many different kinds that you can try out – different guns have to be cared for in different ways. Do not immerse the brush in the bottle, as the brush's ability to clean the barrel would quickly be impaired. Pull the brush through the barrel three to ten times, but be careful when pulling it back out of the muzzle. Once it is out of the muzzle, you can unscrew the brush to prevent it from scouring the muzzle. Leave the solvent on for at least 5 minutes and then wipe it off. Insert a cloth until just in front of the muzzle and check for tombac residue. Repeat the process, if necessary. If you use a cleaning rod guide, you can reduce contamination on the magazine and chamber to a minimum.

    Another cleaning method involves using a paste, not carborundum but special, softer agents. After removing most of the residue with a cloth soaked in oil, wind a cloth round a smaller brush making sure it touches the sides inside the barrel. Apply the paste right round the brush and clean the barrel with the brush. As most deposits occur at the start of the barrel, rub this part with the brush about three to five times longer than near the muzzle. After a short time, you may have to apply more paste. Cleaning with paste is a somewhat messy affair and when you have finished you have to check that there is no paste residue left in the barrel. We have seen barrels that have been destroyed because their owners did not carefully remove all traces of paste after cleaning.

    If you shoot so often with a barrel that hardened residue is difficult to remove, it is best to use paste. You should therefore clean with paste every now and again. Once you have gained some experience, you can tell what kind of cleaning is required. If you also have a borescope (endoscope), it is a great help – it means you can easily inspect the state of the interior bore.


    28. What should I do if I only hear a click?
    Wait at least 30 seconds. Point the barrel in a safe direction (bank of earth) and remove the cartridge. There are generally two possible explanations for it failing to ignite. Either the primer did not ignite as it should or the firing pin could not strike the primer properly. The reason for this could, for example, be a damaged spring, the wrong case or that the breechblock is not closed properly. Make sure that there is nothing in the barrel before the next shot.


    29. What is the difference between the recoil from a normal and a magnum cartridge?
    If you only compare the recoil energy, then it is easy. A .30-06 with standard load and 11.7 g bullet produces energy of 30 J, while a .300 Win Mag with the same bullet but 915 m/s produces energy of 44 J. A .378 Weatherby generates 95 J and a large cartridge such as the .505 Gibbs 149 J.

    The recoil felt depends on how fast it comes and on the weight of the gun. Most people feel that the recoil from a .378 Weatherby is greater than from a .505 Gibbs because of the bullet weight and velocity. You can however effectively reduce the recoil with a good, wide butt plate and a straight gun stock.


    30. Can I use different primers without any problems?
    All primers are suitable for the intended purpose, but you should not use different types of primers. If you use another primer, the firing point may change. The difference can be 10 m/s, depending on the primer, with the pressure also changing accordingly. The primers are likely to have some effect on the barrel vibrations and with that on the precision and target location.


    31. Why does the bullet flight path not correspond to the table data?
    Before a true comparison can be made, the test conditions have to be exactly the same. The stand, the gun's firing position and the shooting angle all have to be same, for example, to ensure that the reason for different target locations is not something other than the projectile's flight path.

    One reason may be that the velocity is not the same. All manufacturers measure the pressure and velocity of barrels that correspond virtually to the minimum dimensions both for chambers and barrels. This is done for safety reasons. Gunsmiths also try to prevent problems with excessive pressure and take certain plus tolerances into account in their dimensions. If these dimensions are greater than the ammunition manufacturers', there will be reductions in pressure and velocity.

    Short or worn barrels naturally also result in lower velocity. In all probability there are bullet manufacturers who determine their ballistic coefficients with calculations and not with measurements after firing shots. If the BC used for calculations is too good (e.g. 0.45 instead 0.38), the projectile flight path obtained will be straighter than it actually is.


    32. What substances does a primer contain?
    The recipe frequently has the following constituents: barium nitrate, lead styphnate, calcium silicide, lead dioxide, antimony sulphide and tetrazene.

    A primer normally contains a priming compound of approx. 30 milligrammes.


    33. Why are some cases nickel plated?
    There can be several reasons for this. If you keep cartridges on a leather belt, the tannic acid soon causes a patina to form on the brass. As a result, African cartridges often have a nickel-plated case. Many people also think that nickel-plated cases look more attractive. The friction between steel and nickel is greater than between steel and brass. It is therefore conceivable that the case is extended slightly less in the chamber.


    34. What are the differences between cold-hammered, button-rifled and cut-rifled barrels?
    The raw material for a hammered barrel is a relatively thick steel blank, which is worked by drilling, grinding and polishing. It is then placed over a mandrel and shaped by hammering. The shape of the mandrel corresponds to a reverse image of the barrel including grooves and lands. Hammered blanks are often polished afterwards. Finally, the chamber for certain calibres is also worked by hammering. It only takes a few minutes to produce a barrel in this way but the machinery is very expensive, which is why only larger manufacturers use this method.

    Button-rifled barrels are also made by drilling, grinding and polishing. The rifling pattern is then pressed into the barrel with a tool called a button. Afterwards the barrel is polished with a lead rod and grinding paste. This method is frequently used by smaller manufacturers, as it does not require such expensive tooling.

    The oldest method of rifling barrels is by cutting. The first steps are the same as for the other two methods described above. A tool fitted on the end of a rod then moves through the barrel, forming the grooves by gradually cutting deeper and deeper on each pass. This method is very time consuming.

    Good barrels can be made with all these methods. Button or cut-rifled barrels are generally the best.


    35. How do you test fire a gun?
    With a rifle scope. You should use a good stand to ensure that the gun is stable. Aim the barrel in the direction and focus the telescopic sight on the target. You can then start test firing. The target should be large enough and complete. Try different settings when shooting until you are satisfied with the results. Check the gun again once or a few times at a later date.


    36. How far does a bullet travel?
    It depends on the type of bullet, the velocity and the firing angle. Bullets generally travel furthest if fired at an angle of 30-34 degrees.

    A .22 LR will fly approx. 1.5 km. A .6.5 hunting bullet can travel nearly 5 km and a heavy .30 projectile even 500 metres further.

    In view of this fact, the target should be taken into consideration.
     
    Last edited by a moderator: May 20, 2014
  2. Royal27

    Royal27 BRONZE SUPPORTER AH Elite

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    Interesting on the humidity level for ammo storage. I have always thought the basement might not be the best place for ammo, but it appears I would be wrong.
     

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