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Techniques

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Measuring land and groove impressions
Courtesy of Ronnie Freels

Measurements may be taken by a number of techniques. Regardless of the microscopic technique, the reference points must simultaneously be in focus; the slightly rounded surface between them may be slightly out of focus.

Land and groove impressions on damaged bullets may not be visible and/or measurable (useable). While it may not be necessary to take all measurements, it is important to take reliable measurements.

Examiner’s notes should reflect

number of visible land and groove impressions,
number of measurable land and groove impressions,
measurements of useable land and groove impressions,
measurements expressed to the nearest thousandth of an inch.

Dashed lines indicate damaged impressions; reliable measurements could not be taken.

Example
As an example, the results accumulated around the circumference of a 380 Auto caliber bullet could be included in a worksheet as:
Land width dimensions/Land impressions	118	121	119	---	121	---
Groove width dimensions/Groove impressions	138	142	---	139	141	140

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