FIREARMS
401. 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. Check out our video clip!
402. 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.
403. 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 calibers have a twist rate of one turn in 8 to 16 inches.
404. 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.
405. Why does muzzle flash sometimes occur?
A normal bullet releases about three liters 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.
406. 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.
407. What is the difference between rimfire ignition and centerfire ignition?
Rimfire cartridges have the priming compound in the rim of the case, such as in a .22 LR. In centerfire cartridges on the other hand the firing pin strikes the primer at the center of the case to ignite it with the priming compound located between the brass cup and the anvil.
408. 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.
409. 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 caliber, 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 caliber x case length. There are several cartridges with the same designation, which does not lead to clear classification.
410. 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.
411. 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.
412. 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.
413. 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.
414. 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 calibers 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.
415. 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.