Priming mixture

Abstract

A priming mixture is described, comprising aluminum silicate in a quantity not exceeding 30% and preferably in a quantity ranging from 15 to 25% by weight, titanium in a quantity ranging from 1 to 10%, preferably from 2 to 7% by weight, samarium oxide in a quantity ranging from 5 to 20%, preferably from 8 to 16% by weight, all quantities referring to the total weight of the priming mixture.

Claims

1. A priming mixture characterized in that it comprises aluminium silicate in a quantity not exceeding 30% by weight, titanium in a quantity ranging from 1 to 10% by weight, samarium oxide in a quantity ranging from 5 to 20% by weight, all quantities referring to the total weight of the priming mixture.

2. The priming mixture according to claim 1, wherein the titanium is in a finely divided metal form.

3. The priming mixture according to claim 1, wherein the mixture also comprises a potassium compound in a quantity of over 10% by weight, with respect to the total weight of the priming mixture.

4. The priming mixture according to claim 1, wherein the mixture also comprises diazodinitrophenol in a quantity ranging from 22 to 32% by weight, and tetrazene in a quantity ranging from 2 to 7% by weight, with respect to the total weight of the priming mixture.

5. The priming mixture according to claim 1, wherein the mixture also comprises nitrocellulose in a quantity ranging from 2 to 5% by weight, and/or penthrite in a quantity ranging from 2 to 7% by weight with respect to the total weight of the priming mixture.

6. The priming mixture according to claim 1, wherein the priming mixture consists of: diazodinitrophenol in a quantity ranging from 22 to 32% by weight; tetrazene in a quantity ranging from 3 to 5% by weight; potassium nitrate in a quantity ranging from 25 to 35% by weight; nitrocellulose in a quantity ranging from 2 to 4% by weight; aluminium silicate in a quantity ranging from 16 to 24% by weight; penthrite in a quantity ranging from 2 to 4% by weight; titanium metal in a quantity ranging from 3 to 7% by weight; samarium oxide in a quantity ranging from 8 to 13% by weight, all quantities referring to the total weight of the priming mixture.

7. The priming mixture according to claim 1, wherein the priming mixture is selected from the following mixtures: a) diazodinitrophenol 27%; penthrite 2%; tetrazene 4%; aluminium silicate 21%; potassium nitrate 30%; titanium 5%; samarium oxide 9%; nitrocellulose 2%, all quantities being by weight and referring to the total weight of the priming mixture, and b) diazodinitrophenol 25%; penthrite 3%; tetrazene 5%; aluminium silicate 20%; potassium nitrate 31%; titanium 5%; samarium oxide 11%, all quantities being by weight and referring to the total weight of the priming mixture.

8. The priming mixture according to claim 1, wherein the aluminium silicate is in a quantity ranging from 15 to 25% by weight.

9. The priming mixture according to claim 1, wherein the titanium is in a quantity ranging from 2 to 7% by weight.

10. The priming mixture according to claim 1, wherein the samarium oxide is in a quantity ranging from 8 to 16% by weight.

11. The priming mixture according to claim 3, wherein the potassium compound is in a quantity ranging from 30 to 40% by weight.

12. The priming mixture according to claim 3, wherein the potassium compound is potassium nitrate in a quantity over 25% by weight.

13. The priming mixture according to claim 12, wherein the potassium nitrate is in a quantity over 30% by weight.

14. The priming mixture according to claim 4, wherein the diazodinitrophenol is in a quantity ranging from 25 to 30% by weight.

15. The priming mixture according to claim 4, wherein the diazodinitrophenol is in a quantity equal to 27% by weight.

16. The priming mixture according to claim 4, wherein the tetrazene is in a quantity equal to 4% by weight.

17. The priming mixture according to claim 5, wherein the nitrocellulose is in a quantity ranging from 3 to 4% by weight.

18. The priming mixture according to claim 5, wherein the penthrite is in a quantity ranging from 3 to 4% by weight.

Description

(1) FIG. 1 is an exemplary distribution of Gun Shot Residue particles generated from a 9 mm gun using a priming mixture according to an embodiment of the present invention.

(2) FIG. 2 is an exemplary layout of test diskettes for conducting analysis of Gun Shot Residue generated from priming mixtures of the present invention.

(3) FIG. 3 is an exemplary SEM/EDX analysis of Gun Shot Residue resulting from a control priming mixture according to an embodiment of the present invention for use as a reference spectrum.

(4) FIG. 4 is an exemplary SEM/EDX analysis of Gun Shot Residue resulting from a priming mixture according to an embodiment of the present invention described in Example 1.

(5) FIG. 5 is an exemplary REM/EDX analysis of Gun Shot Residue resulting from a priming mixture according to an embodiment of the present invention described in Example 3.

(6) FIG. 6 is an exemplary REM/EDX analysis of a paraffin glove control.

(7) The particles emitted from a firearm at the moment of firing, generally indicated with the acronym GSR (Gun Shot Residues), comprise tens of compounds deriving from the primers, powders and metal of the bullet. Instead of the term gunshot residues, the above abbreviation GSR is therefore often used. Forensic science has extensively studied the composition, morphology and distribution of these particles, as identifying them is of indispensable help in criminal investigations. The distribution of GSR particles of a 9 mm gun, for example, object of the analyses described in the following examples, in all the tests effected, showed that the main ejection direction of the particles is that at 45 towards the right of the firing direction, with the maximum concentration at a distance of about 3 m from the shooter, as illustrated in FIG. 1. The shot generates particles having relatively variable dimensions and the particles deriving from the priming mixture have dimensions smaller than about ten m. The particles of unburned powder from gunshot can, on the other hand, have much larger dimensions, up to about 500 m. Some particles are also detected at a distance of over 10 m from the shooter, most of them however are within 7 m.

(8) A first type of verification that is carried out on the samples collected as part of these investigations, is based on the search for and analysis of the particles forming gunshot residues through the SEM/EDX technique, which envisages the use of a scanning electron microscope (SEM) for observation technique, coupled with an energy dispersion microprobe (EDX), that enables the elemental analysis of the sample, making use of the principle according to which an accelerated beam of incident electrons on a sample causes the emission of the innermost electrons of the atoms of the same sample; the subsequent return to the basic configuration induces the emission, inter alia, of X-rays with a predefined energy, specific for each element and in a number proportional to the concentration of the element which is being analyzed at that moment. With this type of analysis, it is possible to identify the lot of ammunition, consequently attributing the ammunition to a certain supplier, and also identifying the shooter of the firearm.

(9) A second type of verification which is again effected on gunshot residues, through staining methods (Chemigraphy), allows copper particles present in the gun powder (and not in the priming mixture) to be revealed, in order to identify the shooting distance and provide a better reconstruction of the dynamics with which the events took place.

(10) More specifically, the SEM/EDX tests carried out in the examples provided below, were effected applying the following protocol:

(11) SEM/EDX Test

(12) Three test diskettes (diameter 12.7 mm) were fixed to a support (for example cardboard) so that their seats form the angles of an equilateral triangle with a side of 15 cm, as represented in FIG. 2.

(13) The test diskette (SEM) has an adhesive layer facing the firearm.

(14) This arrangement is subsequently hit with the ammunition to be tested, using a carefully cleaned firearm to exclude any contamination due to previous firing tests. A distance of about 50 cm must be kept between the support and the mouth of the barrel. The extension of the axis of the barrel must be perpendicular to the barycentre of the triangle formed by the three diskettes, that must be oriented with the adhesive sheet towards the mouth of the barrel.

(15) By tapping on the cartridge case of one of the cartridges fired, reference gunshot residues become attached to the diskette (reference smoke test sample).

(16) The analysis of the diskettes hit was effected by means of a scanning electron microscope with an energy dispersion microprobe, automatically, comparing with the above reference test sample.

EXAMPLES

(17) Some embodiment examples of priming mixtures according to the present invention and comparative priming mixtures are provided hereunder for illustrative but non-limiting purposes of the present invention.

Example 1

(18) A priming mixture according to the present invention was formulated, having the following composition (weight percentage):

(19) Diazodinitrophenol 27%

(20) Penthrite 2%

(21) Tetrazene 4%

(22) Aluminium silicate 21%

(23) Potassium nitrate 30%

(24) Titanium 5%

(25) Samarium oxide 9%

(26) Nitrocellulose 2%

(27) Said priming mixture applied to ammunition for a calibre 9 firearm was tested to verify its properties in terms of heavy metal residues, stability and ballistic effectiveness at different temperatures, and also in terms of traceability of the gunshot residues.

(28) Heavy metal residues: upon analysis with analysis techniques, such as for example Plasma ICP, the ammunition with the priming mixture according to Example 1 had heavy metal residues lower than 0.01%.

(29) Stability at different Ts: by applying the EPVAT NATO method, it was observed that the ammunition with the priming mixture according to Example 1 is stable and ballistically effective at any temperature from 54 C. to +52 C.

(30) FIGS. 3 and 4 enclosed with the present patent application show the SEM/EDX analysis of the gunshot residues of the priming mixture without titanium and samarium oxide as reference spectrum (FIG. 3) and the gunshot residues of the priming mixture according to Example 1 (FIG. 4).

(31) The samarium signal is in a position which is particularly easy to detect, as it is far from the signals of all the other elements present in the priming mixture. More specifically, the energy of one of the three lines having the greatest intensity of samarium from 1 keV to 15 keV at the Rntgen fluorescence spectrum, is significant and is clearly distinguished from that of the other elements present.

Example 2

(32) A priming mixture according to the present invention was formulated, having the following composition (weight percentage):

(33) Diazodinitrophenol 25%

(34) Penthrite 3%

(35) Tetrazene 5%

(36) Aluminium silicate 20%

(37) Potassium nitrate 31%

(38) Titanium 5%

(39) Samarium oxide 11%

(40) This priming mixture, also applied to ammunition for a calibre 9 firearm, was tested to verify its properties in terms of heavy metal residues, stability and ballistic effectiveness at different temperatures, and also in terms of traceability of the gunshot residues.

(41) Heavy metal residues: upon analysis with analysis techniques, such as for example Plasma ICP, the ammunition with the priming mixture according to Example 2 had heavy metal residues lower than 0.01%.

(42) Stability at different Ts: by applying the EPVAT NATO method, it was observed that the ammunition with the priming mixture according to Example 2 is stable and ballistically effective at any temperature from 54 C. to +52 C.

(43) Also in this case, the samarium can be clearly identified, even when present in lower quantities with respect to those present in Example 1.

Example 3 (Comparative)

(44) A priming mixture was formulated, having the following composition (weight percentage):

(45) Diazodinitrophenol 25%

(46) Penthrite 3%

(47) Tetrazene 5%

(48) Aluminium silicate 20%

(49) Potassium nitrate 31%

(50) Titanium 5%

(51) Cerium oxide 5%

(52) Lanthanum oxide 4%

(53) Nitrocellulose 2%

(54) This priming mixture, also applied to ammunition for a calibre 9 firearm, was tested to verify its properties in terms of unequivocal analysis of the gunshot residues.

(55) FIG. 5 enclosed with the present patent application shows the REM/EDX analysis of the gunshot residues of the priming mixture according to comparative Example 3, whereas FIG. 6 shows the REM/EDX analysis of a sample obtained from the paraffin glove test of a person who had not fired. The possible metals resulting in the spectrum of FIG. 6 are consequently not due to gunshot residues, but to environmental pollution due to the working environment (for example bodywork operator, mechanic) or quite simply to the use of objects that can cause a contamination of the user with said metals (for example the use of cigarette lighters). FIG. 6 indicates that lanthanum and cerium can be present in the environment and this makes the measurement based on the identification of these metals unreliable and not univocal: by comparing FIG. 5 with FIG. 6, it is evident that the presence of traces of said metals in FIG. 5 cannot be associated with certainty with the presence of cerium/lanthanum in the priming mixture and not attributable, on the other hand, to the cerium/lanthanum already present in the environment (as indicated in FIG. 6).