SABATTI - MMR® multi-radial rods. Our goal was to create a rifling that had performances at least comparable to the conventional one but with some substantial improvements compared to it. Comparing the 3 scoring profiles shown below: 1) CONVENTIONAL, 2) POLYGONAL, 3) MULTIRADIAL, we realize that the latter summarizes in itself many of the most desirable characteristics both for the use of monolithic and conventional bullets.
In fact, the bullets are deformed according to an arc of circumference and not carved as in conventional rifling (fig. 1), ensuring a long life of the barrels, moreover there are no edges that are impossible to fill as in the case of polygonal rifling (fig. 2). In the MULTIRADIAL rods (fig. 3) two different rays alternate in order to slightly deform the geometry of the bullet but without carving it, thus avoiding excessive stress on the bullet itself. The tests carried out provided us with interesting data:
Le MULTIRADIAL rods in both calibers produced so far: the cal. 7,62mm (.308 ") and the cal. 6,5mm (.264 ”) performed better than our conventional rifling barrels, using both traditional and monolithic bullets. We detected higher exit speeds, in some cases up to 12%, compared to a conventional rifling with normal pressure values, this is due to the fact that the bullet is able to seal the barrel bore much better by limiting the forward leaks of the gas and therefore using the energy of the propellant more efficiently, it must also be considered that the carving efforts and therefore the friction between bullet and barrel are significantly reduced. The size of the groups has decreased on average, this is mainly due to the very tight tolerances that we were able to maintain by producing the MULTIRADIAL rods. In fact, this particular type of rifling lends itself particularly well to being made by cold hammering so that the geometric constancy of the rifling profile was excellent along the entire barrel and, consequently, the barrels that gave mediocre results have practically disappeared. . The number of fliers has been drastically reduced, this can be largely attributed to the particular geometry of the forcing cone, in fact the MULTIRADIAL rifling generates a geometrically different forcing cone that is able to insert the ball in a more secure and precise way in the grooves, forcing the bullet to better align with the barrel axis.
The copper deposits inside the MULTIRADIAL rods, all other conditions being equal, they are lower than conventional scoring, requiring less frequent cleaning and limbing and much easier to perform. Finally, we verified the possibility for the end user to significantly improve the performance of the MULTIRADIAL rods simply by lapping the hole with pads and abrasive paste, without running the risk of ruining the edges of the lines.
Thanks to these characteristics the MULTIRADIAL rifling it proved to be particularly suitable also for sporting and competitive use, so much so that, according to the requests of our shooters, all shooting rifles cal. 308 Win. of the company Sabbath they are now equipped with MULTIRADIAL grooves. We believe we have achieved all the objectives that we set ourselves in the design phase, moreover, the results obtained during the experimentation went beyond our expectations.