Surface damage from perpendicular and oblique bullet impacts in stone

Area of Science:

• Geology
• Materials Science
• Archaeology

Background:

• Cultural heritage sites in conflict zones face damage from projectiles.
• Understanding ballistic impact effects on building materials is vital for conservation.

Purpose of the Study:

• To investigate surface damage from bullet impacts on sandstone and limestone.
• To compare crater characteristics from different ammunition types and impact angles.

Main Methods:

• Controlled firing experiments using rifle ammunition (5.56 × 45 mm NATO and 7.62 × 39 mm).
• Analysis of crater dimensions (diameter, depth) and morphology on sandstone and limestone targets.
• Examination of fracture patterns and asymmetry due to oblique impacts.

Main Results:

• Craters ranged from 22-74 mm in diameter and 3-24 mm in depth.
• Limestone craters were larger, deeper, and more complex than sandstone craters, often exhibiting radial fractures.
• Oblique impacts (45°) created asymmetric craters.
• The 5.56 × 45 mm NATO projectile generally caused larger craters than the 7.62 × 39 mm projectile.

Conclusions:

• Ballistic impacts cause significant, material-dependent surface damage to stone.
• Crater morphology and extent are influenced by rock type, projectile characteristics, and impact angle.
• Findings inform conservation strategies for cultural heritage sites affected by conflict.