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() oo The leaded condition made it very difficult to determine whether a particular bullet could be matched up with the revolver on a sub- sequent test fire. Even though the gross imperfections (double furrow gouge) were found repeated on all the 1975 test-fired bullets, reproduced in a shot for shot basis, the severe leaded ee Saat ak Sete inet eer Set mee = wea ee ad Veo. Sses bite Se Fett Se 4 TPSeVEY condition of the barrel made it difficult to match up individual characteristics of the 1975 testfired bullets with any of the 1968 evidence bullets and Wolfer fired bullets. The experts conceded that the dirty and leaded barrel could possibly change striations and characteristics on fired bullets. None of the experts could give any explanation for the leaded barrel, and one, Patrick Garland, even surmised the possibility that the barrel had been fired during the time elapsing since 1968 and prior to the 1975 examination and testing The nature of the leaded barrel was such Mer SR ee ed ‘pe Oe ee ee ee OO ee that it severely reduced the chances of identifying the individual characteristics, or striations, that were formed on fired bullets as a result of the manufacturing process of the weapon barrel. These individual characteristics are a basis for the identification of the individual marks. Search for Individual Soecific Characteristics Even though the Sirhan weapon ha entifiable muzzle defects at the 300° to 360° end of the muzzle (in the Land #6 and Land #1 area), there were definite repeating gross individual charac- teristics that were far more identifiable than specifie individual characteristics and gave the experts the feeling that there was no evidence of any nature to suggest another gun had fired any of the bullets. Even though al] the examiners stated that tney had different thresholds of identification before they could make a positive identification, they felt that the individual lines and trtiatin a hm hi: : 2 : striations of each bullet fired meant a very high percentage in favor of the fact that all the bullets had been fired from the same weapon. Inherent in this was the concept of consecutiveness, the fact that individual characteristics were associated with each other in a relation to the driving edge of the barrel as the bullets spun out of the barrel. In the area of particular gross characteristics, again due to barrel damage effect, even the 1968 Wolfer test fired bullets showed indications of particular gross characteristics, which gave Fiint hb ftadin that _ further indication that no second gun had been fired. As an addi- tional attempt to try to further identify individual charac- teristics, as well as the gross imperfections, the experts attempted to reproduce these defects. Casts were made of the forward end of the barrel, the casts being prepared using duplicast Silicone solution. But the experts concluded that the casts were not suitable for microscopic examination of the imperfections in the barrel. Next, a new attempt was made with a mixture of sulphur and lamp black melted and poured into the muzzle of the Sirhan révolver to cast the front 1/4 to i/2 inch of the barrel. These casts were examined microscopically, and the experts found that although some defects of the muzzle were reproduced, cast shrinkage during cooling detracted from the quality of the cast. The experts concluded that orientation of the imperfections from the barrel to bullets was not possible. a - 28 - O