Forensic Examination of Modified Rifled Firearm

Dinesh Sahu; Harshita Bose

Forensic Examination of Modified Rifled Firearm

Author(s)	Dr. Dinesh Sahu, Ms. Harshita Bose
Country	India
Abstract	Illicit modification of factory-manufactured firearms has emerged as a significant challenge for forensic firearm examination, particularly when legally manufactured weapons are altered to chamber and fire unauthorized ammunition. This study aimed to investigate the mechanical alteration of a factory-made .303 British bolt-action rifle modified to chamber and discharge 7.62 × 51 mm cartridges, while evaluating its structural modifications, ballistic performance, and forensic significance. The firearm underwent detailed visual and mechanical examination, dimensional analysis of the chamber using a precision Vernier caliper, controlled test firing, muzzle velocity measurement using the BMS software, and forensic examination of fired cartridge cases. Comparative analyses were conducted with a standard .303 British rifle and a standard 7.62 × 51 mm self-loading rifle (SLR). Examination revealed that a metallic lining had been introduced at the shoulder-to-neck junction of the chamber, reducing its diameter to accommodate the smaller cartridge. Test firing confirmed the successful functioning of the modified firearm; however, it exhibited a substantially reduced muzzle velocity compared with the standard .303 British rifle and SLR. Fired cartridge cases also displayed characteristic bulging due to inadequate chamber support and abnormal pressure distribution. The findings demonstrate that localized chamber modifications can effectively convert a .303 British rifle to fire 7.62 × 51 mm ammunition, albeit with compromised ballistic performance and increased mechanical risk. The study highlights the forensic importance of dimensional chamber analysis, ballistic testing, and fired cartridge case examination in identifying illegally modified firearms, thereby providing valuable scientific evidence for forensic laboratories and law enforcement investigations.
Keywords	illicit firearm modification; forensic ballistics; .303 British rifle; 7.62 × 51 mm cartridge; chamber alteration; muzzle velocity; firearm identification; forensic firearm examination
Published In	Volume 8, Issue 5, September-October 2026
Published On	2026-09-11

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International Journal For Multidisciplinary Research

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Forensic Examination of Modified Rifled Firearm

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