Manufacturing of barrels

Barrels manufacturing

The more precise barrel geometry is, the more accurate the rifle on which it is installed will shoot. Behind this simple proposition lies centuries-long experience in the development of firearms production, immense engineering and intellectual work and outstanding skills in working with complex tools and instruments. Barrel is the most complex component of high-precision firearms which requires a lot of special equipment for its production.

Only high-quality gun barrel alloys are used as feedstock for manufacturing ORSIS rifles: 416R grade stainless chrome steel and 4140 grade chrome- molybdenum steel.

08_MG_9568.jpg

High-tech tools and unique techniques make it possible to manufacture barrels with a caliber ranging from 5.6 mm to 22 mm with a barrel length of up to 1,050 mm and any pitch of rifling (including variable), any number of grooves (including an uneven number), any ratio between the rifle lands and grooves, and the groove contours. All processes related to the production of ORSIS barrels, including deep drilling, barrel finish reaming, and chambering, take place within the manufacturing facility. The key stage in fabricating high-precision rifle barrels is the rifling work that is performed in two ways in the Promtechnologies factory: via the button method and single-point cut rifling. The barrels for all high-precision rifles worldwide were made using one of these technologies.

Rifling: single-point cut rifling (surfaced using a cutting tool) is the best technique available for making barrels. Single point cut rifling is frequently referred to as “the technique of champions”, since most world shooting records are set using rifles with barrels manufactured using this method. A special cutting tool called a “hook cutter” makes a groove each time it is pulled through the chamber. All in all, the cutting tool should pass 80-100 times to complete a groove. The machine tools used for single-point cut rifling are designed in the company’s development laboratory with input from consultants and suppliers of parts and components from Switzerland and Germany.

Rifling: single-point cut rifling

Rifling: single-point cut rifling (surfaced using a cutting tool) is the best technique available for making barrels. Single point cut rifling is frequently referred to as “the technique of champions”, since most world shooting records are set using rifles with barrels manufactured using this method. A special cutting tool called a “hook cutter” makes a groove each time it is pulled through the chamber. All in all, the cutting tool should pass 80-100 times to complete a groove. The machine tools used for single-point cut rifling are designed in the company’s development laboratory with input from consultants and suppliers of parts and components from Switzerland and Germany.

By taking classic English machine tools for single-point cutting, retrofitting them and developing an original computerized control system, Promtechnologies experts managed to achieve a radically new technology. This approach makes it possible to obtain a virtually ideal bore: deep groove precision less than 0.001 mm, and rifling pitch precision of 0.04 mm. Surface finishing for rifling marks reaches Rz 0.16 microns, and Rz 0.8 microns for grooves. Barrels manufactured using this technology are regarded as a work of engineering art, and are considered to be among the best in the world. The Promtechnologies Moscow-based weapons production facility is one of the first in Europe to manufacture high-precision rifle barrels using the single-point cutting method on CNC machine tools.

Rifling: button method

Button rifling (button method) is a method for manufacturing rifle barrels using a special tool, a mandrel, which is stretched under pressure through the bore hole, using the decreasing lubricant friction. The mandrel is a carbide-tipped tool made of tungsten carbide with a hardness of about 75 units on the Rockwell scale. When moved, the contour of a mandrel with a diameter larger than the bore, squeezes out the groves into its inner surface. After this, the barrel is thermally treated in a digitally controlled sintering type electric oven, which features staged heating, long-duration holding and slow cooling of the barrel (about 10 degrees per hour). At this stage of the barrel production process, two tasks are solved simultaneously: metal tension is relieved and the bore hole is gradually squeezed to the required size. The entire thermal treatment takes about two days.

The Promtechnologies weapons production facility is the only Russian manufacturer of barrels using the button method.

.

Production process Chambering

The experts of Promtechnologies are no less diligent in their approach to manufacturing rifle chambers. For this type of work, both computerized and digitally controlled conventional lathes are used. Making a precision chamber is nearly an art, and for this reason the tools used for this purpose were retrofitted in the company’s development laboratory. Special devices are installed on both sides of the spindle, which make it possible to line up the position of the barrel during the rifling process. This way, before the reamer touches the barrel, dial indicators in the bore show the rotary action with an accuracy of no more 0.002 on both side of the barrel. This makes it possible to achieve the best possible alignment (linear arrangement of the axes) of the chamber and the bore, which means that shooting accuracy will be even higher.

Furthermore, for these operations, special pilot reamers and floating chucks are used, as well as a special system for polishing the chamber and the bullet chamber. To connect the barrel with the action a special full contour staggered cut is made which makes it possible to achieve an exceptionally tight fit, evenly distributing the load on the turns of a thread when the rifle is fired, while minimizing or completely eliminating the cold barrel effect.

Most chambers can be made to C.I.P or SAAMI standards with a short or long bullet chamber, based on the customer’s specifications.