If you find yourself concerned with the dimensions or width of the current sense resistor BR3FB5L00 from Stackpole Electronics Inc, then looking into the datasheet may be confusing.
The datasheet does not specify the width or any other dimension for this product. The width shown in the images below is determined by the material used for this combination of size and resistance value. This implies that the width of such a resistor depends on the material used for the given value of resistance.
Specifically, for the MPN# BR3FB5L00, the element material has ¼ inch width, therefore the measurements shown by Vernier are perfectly reasonable for what this part would be expected to measure.
Different resistance values will require significantly different material widths and therefore this dimension can vary widely. To define the dimension for the full value range would require a tolerance that would make the dimension information meaningless.
Applicable Part Number
DK# BR3FB5L00-ND