Mercury ammunition

Impulse of a Primer. When a primer is fired, the force of detonation or length of spit is called impulse. It is measured by the maximum displacement of a mercury column resulting from the firing of the primer in an apparatus shown in Fig 15, p 50 of T.C. Ohart, Elements of Ammunition, J. Wiley, NY (1946)... 

Other incendiary compositions used in older ammunition were potassium chlorate based with a mixture of potassium chlorate and mercury sulfocyanide as the priming composition. Another older incendiary composition consisted of potassium nitrate, magnesium, aluminum, and lead oxide.72,73 Multipurpose filled bullets are also manufactured, for example, armor piercing/incendiary, armor piercing/tracer, and spotter tracer bullets, which leave a visible trace and produce a puff of smoke on impact. One such smoke charge is lead dioxide 85% and powdered aluminum 15%. There... 

At the start of 1978 the particle analysis method183 replaced the flameless atomic absorption bulk elemental method184 as the firearm residue detection method in the NIFSL. Since then the particle analysis method has been substantially improved by the use of a sample concentration/cleanup procedure,185 the addition of a backscattered electron detector, and the development of an automated residue detection system.186 187 Despite these improvements the technique remains costly and labor intensive. Certain aspects of the system required further work, in particular, the particle classification scheme discharge particles from mercury fulminate-primed ammunition and discharge particles from new primer types (Sintox). 

The particle classification scheme is based on modern primed ammunition and consequently mercury fulminate-primed ammunition is not included. Mercury-containing particles from the discharge of mercury fulminate-primed ammunition are rarely detected in casework. Discharge residue from such ammunition was tested in an effort to provide an explanation for this. Discharge particles from Sintox-primed ammunition was also examined with a view to anticipating future problems the criminal use of... 

The presence of Sn suggests mercury fulminate-primed ammunition. (Sn is present in some propellants it has been used to harden bullet Pb and it is present in some bullet jackets.)... 

It is interesting to note that the primer appears to be based on mercury fulminate, antimony sulfide, and potassium chlorate, that is, mercuric and corrosive, and that the ammunition was manufactured in 1982. 

There is no lead or barium in the primer yet discharge particles from this ammunition frequently contain lead, antimony, and barium. The lead and barium must come from other components in the ammunition (bullet core/propellant) and/or from contamination in the firearm. Tin was also frequently present in the discharge particles and originates from the tinfoil disc used to seal the primer cup in mercury fulminate primers. 

The analysis of primers supports the statement that Communist Bloc countries frequently use mercury fulminate primers and it is also worth noting that the same applies to ammunition manufactured in France, at least for the time period involved. According to the literature there has been no mer-... 

Analysis of the nny 82 ammunition as previously detailed shows that it uses a mercuric corrosive primer. Analysis of the Chinese 351/73 ammunition revealed that it has a copper-coated iron-jacketed bullet with an iron core and a lead tip, the cartridge case is steel with a brown colored lacquered finish, a brass primer cup, and the propellant is single based with DPA, 2 x nitrodiphenylamines, camphor, and contains no inorganic additives, and the discharged primer composition is antimony, potassium, chlorine, mercury, tin, sulfur, iron, manganese, phosphorus, zinc, and lead in descending order (lead, antimony, mercury type). 

The frequent use of both types of ammunition in recent years has substantially increased the proportion of shooting incidents involving the use of mercury fulminate-primed ammunition. It has also substantially increased the proportion of shooting incidents involving the use of single-based propellant. It is worth noting that both propellants contain camphor. 

The particle classification scheme, developed as described in reference 200, did not include mercury fulminate-primed ammunition, which is frequently encountered in Northern Ireland, and is currently manufactured in some Eastern Bloc countries. 

In casework in which discharge residue particles were detected, and in which the ammunition involved is known to contain mercury, very few, if any, of the particles contained mercury. This has been noted over many years and in numerous cases. Possible reasons for this could be the volatility of mercury and its compounds, or decomposition of the mercury fulminate and the loss of mercury through amalgamation with zinc in the primer cup/car-tridge case. It is not uncommon, when firing old ammunition with mercury fulminate primers, for some of the cartridge cases to crack, due to embrittlement of the brass caused by mercury amalgamating with the zinc. 

To clarify the situation regarding mercury-containing ammunition a series of experiments were conducted and casework statistics gathered. 

To determine the frequency of occurrence of mercury-containing particles in FDR, promptly collected residue from the discharge of mercury fulminate-primed ammunition was examined. Results are given in Table 22.1. In the first firing a small proportion of the particles also contained one of the following elements cobalt (trace), magnesium (trace), nickel (trace), and phosphorus (minor and trace). 

On other occasions mercury-containing ammunition has been test fired, the hands sampled immediately, the samples analyzed by SEM/EDX, and... 

This supports the proposition that anything present in a round of ammunition can make a contribution to the composition of the discharge residue particles. The presence of tin in any of the discharge particles is an indication that the primer contains mercury, the tin originating from the tinfoil disc used to seal mercury fulminate. (Tin is also present in some modern ammunition components, for example, Sellier Bellot, and it is present in some propellants.)... 

A specific ammunition type was examined to determine the total mercury content. Results are given in Table 22.4. 

These tests give an estimate of the total amount of mercury in a complete round of ammunition prior to discharge (4,070 pg), the amount deposited on the bullet (2.15 + 16.78 = 18.93 pg), the amount remaining in the spent... 

The mercury concentration remaining in the spent cartridge case was considerably higher than previously experienced. This test did not reproduce the conditions experienced during the discharge of a round of ammunition, where much higher temperatures and pressures are attained, plus the possible suction effect in the wake of the bullet. To simulate actual conditions a further test was devised (Figure 22.2). 

A percentage recovery of 48.73 is disappointing. The variation in the amount of mercury initially present in the ammunition (see Table 22.4) is probably due to deterioration of the mercury fulminate over a long period, the ammunition having been manufactured in 1943. The variation would... 

An ancillary test involved examining discharge residue particles from the ammunition used in the mercury distribution tests. Approximately 260 particles were examined of which 8 contained mercury (about 3%) at minor or trace level. 

A. Zeichner, N. Levin, and M. Dvorachek, Gunshot Residue Particles Formed by Using Ammunitions That Have Mercury Fulminate Based Primers, Journal of Forensic Sciences 37, no. 6 (November 1992) 1567. 

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