Rules for firing in fortress-siege artillery
The first Проекто-правила за стрелбата въ крепостно-обсадната артилерия (Draft rules for firing in fortress-siege artillery) published in 1897 were revised according with the remarks and the proposals of the officers, who had applied them in the firing practice, and adopted in their definitive version with Order N° 26 on 17 October 1900.
According with the experience gained, the following changes were introduced :
1) narrowing down the low bracket up to 4-2 probable deviations;
2) repetition of the limits of the low bracket;
3) passing to the centre of the bracket or to one of the limits (on straddle) and carrying out the group;
4) introduction of more precise rules for finding the correspondence between the bursting time of the fuze and the elevation obtained with the percussion adjustment;
5) introduction of control shots and indication about when and how they were to be carried out.
However narrowing down the low bracket up to 2 deviations was allowed only for known calibre guns, since the firing practice had shown that the probable deviations of their tables were about 2-3 times greater than the real ones obtained with 3 inch mortars, and the dispersion of the 9 pdr and 4 pdr guns was much greater than that indicated in the tables. Since in the plunging fire the charge was changed, the width of the short bracket at 2 probable deviations was required to carry out the shot with the fixed charge, especially when the angle of elevation was close to 38°.
The repetition of the limits of the short bracket was required by the fact that firing in the fortress-siege artillery had to be methodical and precise, for example with the dismantling fire. By means of the repetition of the limits, the probability of hitting the target in the effective area rose up to 83%, while with the single limit it was only 53%. Indeed, methodical and accurate shooting with repetition of the limits reduced the rate of fire; however, this was not important for the fortress-siege artillery, since its targets did not move away quickly.
The transition to the centre of the bracket or to one of the limits was a consequence of repeating the limits of the short bracket.
Finally, the revised rules added the guidelines for regulating the shrapnel fire, introducing the correspondence between the interval and the height of the burst in relation to a specific target.
Only two years after the publication of the new rules, the Artillery Inspection issued a detailed directive, which presented the whole question of the use of fortress-siege artillery in a complete and organic way. It remained in force until the introduction of quick firing artillery.