Universal reamer 9x18 made of 9XC steel designed for unfolding and repairing the chamber. Used primarily for pistol cartridges.
The use of a reamer not only allows you to accurately comply with all dimensions, but also increases the resource of the barrel, contributing to the preservation of rifling. The reamer makes a bullet entrance, which clings to the edge of the sleeve. In the case of using an ordinary cutter, there is no bullet inlet, the sleeve rests against the grooves and deforms them over time, as a result of which the cartridge begins to fail.
* Made on factory equipment
* Tool alloy steel 9ХС. Possesses increased wear resistance, fatigue strength in bending, torsion, contact loading, as well as elastic properties.
Note that the reamer does not groove. A mandrel is used for this purpose.
Rifle barrel manufacturing process
No small arms manufacturer will ever tell you exactly how they make precision sport rifle barrels and benchrest rifles. It's always a mystery. Each manufacturer has its own. Whether it's Feinwerkbau, Steyr, or Walther - everyone has their own secrets, which they don't spread because they got them, or from other generations of old manufacturers of high quality gun barrels, or they got the right production technology by their mistakes. After all, look: the trigger mechanism - here it is, take it apart, repeat it, and study it, everything is in plain sight. And how the barrel of a rifle is made, what is the secret of the high performance of the barrels when firing from the machine - this is only given to the manufacturer to know. Their secrets are the path to sustainable production success.
One often hears the opinion that high quality weapons can only be achieved at huge arms factories, using expensive technologies, equipment, and infrastructure. However, practice shows that the most accurate and perfect samples of rifles are collected practically by hand. I have seen many small workshops in the United States employing one or two or three people and still producing rifles or weapon components of the highest standard. Often, such small companies can be suppliers of some components for large industries.
A sporting rifle, or benchrest (or any other), consists of four main parts: a stock, a bolt action, a trigger and a barrel.Usually gunsmiths who assemble rifles don't make anything themselves, they buy ready-made components and put them together. However, this is just in words, experience, knowledge and special tools are required.
How high precision rifle barrels are made
First of all, having received any component, the gunsmith checks and measures it very carefully. The barrels are inspected along the inner channel, it is measured with special digital bore gauges, adjusted to the ring gauge. Each ring gauge has a special certificate indicating its exact size to 6 decimal places (in inches), or to a quarter of a micron in millimeters. A bore gauge adjusted to this caliber shows the true value of the barrel dimensions down to microns. If the values do not suit the gunsmith (for example, one rifling is slightly deeper than the others, per micron), then such a barrel is rejected for benchrest and will be used to make a hunting rifle or will be returned to the manufacturer. The barrel is also subjected to a thorough visual inspection using an optical instrument - a borescope, the cleanliness of the inner surface, the absence of tool marks or any minor damage is assessed. After that, the gunsmith on a special band saw saws off the end of the barrel (about 5-6 mm), and the sawn-off piece passes the Rockwell hardness test on a special hardness tester.
If all the values suit the gunsmith, he proceeds to cutting the chamber and connecting threads. But first, the bolt group is carefully measured and checked. The requirements for tolerances here are no less stringent, but in addition to checking the geometry and hardness of the body of the group, the gunsmith checks the force of the mainspring with a special device, evaluates the quality of grinding the ends of the spring and, if required, modifies them. The size from the shutter mirror to the end of the body of the shutter group is very carefully checked. This dimension is important for setting the mirror gap. In sporting and benchrest rifles, it is minimal, so the preparation is very thorough.
After the barrel and the bolt group have been tested, you can start connecting them together. There are many ways to open the chamber, I have personally seen seven different options, but the most difficult is used precisely for deploying the chamber of benchrest rifles.
The gunsmith uses a small lathe, which, in addition to high precision, must have two important qualities: the spindle tube must be shorter than the barrel, and the spindle bore must be at least 40 mm. The usual cartridge is removed, and a special adjusting device is installed instead. A special device is also put on the outer end of the spindle tube, the barrel is set in beating on both sides in order to exclude the slightest effect on the axis of rotation and the trajectory of the sweep during operation.
Preliminarily, from the side of the chamber, the barrel is pressed with the center and the beating is eliminated (according to the hour indicator) from the opposite side of the barrel (from the outer end of the spindle tube). After preliminary installation of the barrel, the gunsmith installs the indicator on a magnetic stand, the measuring lever enters the barrel bore from the side of the future chamber and begins to adjust the screws of the device, eliminating the slightest beating. The indicator is used on a scale of one ten-thousandth of an inch, or two and a half microns. After the arrow of the indicator stops showing the deviation, the barrel is considered to be installed. The procedure can take from half an hour to 45 minutes.
Further, the gunsmith grinds the barrel for threading with a margin of a couple of "tens", but cuts the thread only after the chamber is unfolded.
Four tools are used to unroll the chamber: drill, cutter, rough and finish reamers. Sweeps are used with interchangeable pilots.Such a pilot does not rotate in the bore and does not leave marks on the bullet entrance, however, working with such sweeps requires more care, chips can get between the pilot and the body of the sweep and ruin the whole work. The reamer is fixed in the tap holder and held by hands, the shank is pressed by the center of the tailstock and fed by the lever of the tailstock, the feed size is controlled by the digital display device of the machine. The operation is slow, the sweep is removed from the channel during operation and cleaned (the pilot is examined through a magnifying glass) from chips and lubricated.
To control the dimensions of the chamber, a digital depth gauge is used, fixed in a special device - a "glass". A check gauge is installed in the chamber, the "glass" is pressed against the end of the barrel, which will be in contact with the end of the bolt group, and the distance to the base of the caliber is measured, by this value the gunsmith knows how much more metal needs to be removed to get "zero".
After the chamber is deployed to the desired depth, the gunsmith cuts the thread, the thread is cut with a special profile and differs from the usual counter thread.
The gunsmiths pay even more attention to the quality of the thread than the chamber, the correct thread ensures a tight fit of the barrel from the first turns, and during the firing process it will provide an even load of all the turns, distributing the load and making the shooting stable and accurate. The thread is measured with special wires and a micrometer, this allows you to control the size of the thread in the center of the turns.
Then the gunsmith processes the end of the barrel with a certain taper angle for the correct position of the bolt and the minimum clearance between the barrel and the bolt after installation.
After that, the barrel is turned over, the process of installation and elimination of beats is again carried out, and after that the muzzle is processed. The barrel is preliminarily measured, weighed and the position of the muzzle is marked, since after processing the barrel must exactly correspond to the weight parameters, since the total weight of the rifle should not exceed 4.7 kg together with the sight and rings, and the weight of each component is critical.
The last operation is the external polishing of the barrel and the engraving of inscriptions indicating the caliber and size of the chamber neck. The next operation is fitting the stock and gluing the bolt group.
The stock is fixed in a special machine and aligned in geometry, the axis of the butt and the support part of the forend must be perfectly perpendicular, otherwise deviations will occur during the shooting process, and the shooting will not be champion.
Not all lodges undergo such a procedure, some, due to the nature of the material, cannot be modified, and they are simply checked for compliance with the parameters. First of all, these are lodges made of Oregon pine and carbon fiber reinforced plastics.
If the stock suits the gunsmith, the gluing process begins. Instead of the barrel, a mock-up is installed - a metal cylinder with a thread. It is needed to check the position relative to the barrel groove of the forend. The layout of the trigger is also installed. All surfaces to be glued are thoroughly degreased, adjoining parts are sealed with masking tape. For gluing, JB weld composition is used, the glued group is kept for about two days before work is continued with it.
After the group is glued in, the barrel is installed. The barrel is lubricated with a special grease from sticking, it is applied abundantly, then wiped with a cloth so that a minimum layer remains. If this is not done, then the barrel will be very difficult to unscrew in the future. Then the barrel is clamped into a special barrel vise, a “key” is inserted into the bolt group and the barrel is tightened with a torque wrench, controlling the tightening force. Grease from sticking the barrel thread. How high precision rifle barrels are made
For front-end rifles, Jewell trigger mechanisms are usually used, but in recent years their quality has deteriorated. The very first mechanisms, released more than twenty years ago, were completely milled, now there is a lot of stamping, the springs do not correspond to the declared forces, the cases do not always have the required geometry. The gunsmith corrects all this, the escapement is disassembled, polished and polished, the spring is installed with the accuracy of force in accordance with the standard, the stamped parts of the case are replaced with milled ones. Checking the dimensions of the hooks is carried out using a measuring microscope. The cost of such work is usually equal to the cost of the escapement, but in the future such an investment pays for itself a hundredfold - the escapement works like a Swiss watch for many years.
After installing the trigger, the rifle is fully assembled. The gunsmith checks the clearance between the bolt and the barrel taper. There is a clever trick here, a thin lead wire is glued onto the shutter cone and the shutter is locked, the wire is crumpled, and these places are measured; if they are equal and correspond to the standard (usually 0.1 mm), then the rifle is considered finished.
This is followed by the installation of rings and a sight, control weighing of the rifle, cleaning and you can go to shoot, knowing that the weapon is assembled flawlessly and all errors at the turn are not barrel errors, but shooter's errors.
Video (click to play).
Alexey Sorokin
