AFTE Store - The Forensic Aspects and Challenges of Winchester’s Tin .22LR Bullets

The appearance of Winchester’s pure tin, 26-grain bullets in their Varmint LF .22 long rifle ammunition, product X22LRHLF, represents a new and interesting challenge for forensic firearms examiners. The first clue that one is dealing with something well outside the norm is the weight of a recovered projectile followed by its exceptionally shiny appearance.

These bullets typically acquire the general rifling characteristics of the firearm from which they are discharged, but not necessarily reproducible striae patterns sufficient for firearms identification.

Although the shape and dimensions of these bullets are virtually identical to their lead counterpart, tin’s substantially lower density compared to that of lead, results in their greatly-reduced weight of 26 grains.

While this lower weight results in a much higher muzzle velocity, it also results in a reduced ballistic coefficient, and a corresponding rapid loss of velocity over time and distance compared to the equivalent lead bullet.

Traditional tests for lead in bullet wipe with the sodium rhodizonate test may be of limited success, or even unsuccessful with
this ammunition because the only sources of lead are the priming mixture in these cartridges and/or ‘pick-up’ from a bore
previously fouled with traditional lead bullets.