The ballistic data for RWS rifle cartridges do not represent absolute values, but are simply average values taken from numerous measurements using weapons of different makes. This data can be influenced to a lesser extent by unavoidable dimensional tolerances in weapon and cartridge production and to a greater extent by different barrel lengths. The firing results for all cartridges are obtained under identical test conditions in the physical-ballistic laboratories and evaluated using modern software. The values in the ballistic data are normally given for horizontal shots fired at 0 m sea level.

The ballistic coefficient describes the bullet-related influences on the delay of the bullet caused by air resistance and is therefore a parameter for the ability of a projectile to overcome air resistance. This delay is dependent on the shape and mass, as well as on the speed of the bullet and the air density. The energy is calculated from the speed and the bullet weight. The energy values are given in Joule (J) for distances from 0 to 300 m.

Trajectory curve
The barrel length is given in addition to the cartridge data. For high performance cartridges, such as the 7 x 64, this length is 650 mm. In general, it is 600 mm for other rifle cartridge calibres. The speed V (velocity) is given in m/s for distances of 0, 50, 100, 150, 200, 250 and 300 m. The velocity increases/decreases by 10- 15 m/s for standard cartridges when the weapon barrel length is 50 mm shorter or longer than the given values. This value can fluctuate by up to 20 m/s (meters per second) for high performance cartridges. It is assumed that the telescopic sight is mounted so that the distance between sight line and bore axis is 5 cm. Positive values indicate high shots, negative low shots. At least three shots are recommended to determine the point of impact position.

 

The SID is the point at which the projectile trajectory crosses the line of sight for the second time. The bullet should not deviate by more than 4 cm from the line of sight. This means, in the example shown here, that the aiming point does not need altering up to a distance of 209 m. The hunter can then concentrate fully on the game and sighting in is still possible at 100 m. At this distance, the 7 x 64 weapon would need to have a high shot of 4 cm to ensure a spot shot (SID). The ballistic table calculations all assume a sight height (distance between telescopic sight centre and barrel axis) of 5 cm. If the actual sight height deviates from this value, the SID will also change. In this case, the gunsmith should sight-in again.

The above graphic shows the shot development over time. The time scale is given in milliseconds (ms). The sequence is divided into different phases, time 0 is where the striking pin hits the ignition cap. The ignition delay time applies from 0 – t1 and represents the ignition charge transformation phase. The ignition phase reaches from 0 – t2, where t2 is defined at the time to reach 10% of the maximum gas pressure. The propellant transformation phase starts with t2 and ends with the falling gas pressure curve once the powder has been fully transformed. The total shot development time is from 0 to t4, i.e. up to the moment where the bullet has reached the muzzle. The graphic shows the bullet speed sequence calculated from the gas pressure course as a dashed line. This shows that the beginning of the bullet movement starts at the end of the ignition phase. The speed of the bullet then increases constantly until the end of the powder transformation phase. Only a minor increase in speed is noted before the muzzle is reached.

Various factors influence the point of impact deviations from one ammunition lot to the other. RWS rifle cartridges demonstrate that ammunition production is set up so that gas pressure is always within the legally applicable limits and that the bullet speed values are uniform from production lot to production lot and comply with the ballistic table. Extremely strict quality parameters are set for the production of ammunition components and upstream checks ensure that tolerance deviations in outgoing components can be avoided. It has been shown, through numerous point of impact tests at our works, that there are "insensitive" weapons, regardless of the cartridge type. These weapons can relatively easily deal with various cartridge production lots. There are however "sensitive" weapons whose point of impact deviations are more apparent. These include combined weapons. Extensive tests show the problems caused by barrel vibration influences and the departure error angles for different ammunition lots of identical cartridge types at identical speeds. These influences cannot be controlled by the ammunitions manufacturer using measures during production, regardless of how careful the production is.

RWS is known for the fact that the point of impact hardly changes from lot to lot. Nevertheless, the obligatory test shot should be implemented when opening a new cartridge pack with a different lot number. For this reason, we recommend that you buy enough cartridges from one production lot to supply you for a longer period of time. This applies in particular to owners of combined weapons with several rifle barrels.