Estimation of calibre from Xrays

Whilst X-rays can be used to accurately locate a missile, they cannot be used to precisely measure the calibre of a missile as all X-ray images, by virtue of the way they are taken, are magnified to some degree. As the distance from X-ray plate to the missile increases, so does this magnification effect.

These problems can be offset by taking two X-ray photographs of the body, one face on and one side on. These can then be used to estimate the depth of the missile in the body. A number of bullets of different calibres can then be placed alongside the body at a suitable position and then X-rayed (Figures 5.1-5.3) to estimate the bullet calibre.

Alternatively, a micrometer, with its jaws open to a set measurement, can be placed in the appropriate position (Figure 5.4) and can be used to estimate the calibre.

The only way an X- ray can be used to directly estimate a bullet -s calibre without the foregoing use of two X-rays taken at 90 ° to each other is to compare the size of the bullet's shadow on the X-ray alongside several bullets of known

How Figure Aaout Bulet Trayectore
Figure 5.1 Bullet deep in the body. Photograph reproduced by permission of Evan Thompson.
Rays Evan Thompson
Figure 5.2 Bullets being placed in an appropriate position. Photograph reproduced by permission of Evan Thompson.
Evan Thompson Firearms
Figure 5.3 Bullet calibre comparison. Photograph reproduced by permission of Evan Thompson.
Ballistics Bullet Comparison
Figure 5.4 Example of how a micrometer can be used to estimate a bullet's calibre.

calibre. Whatever bullet calibre is closest in size to that on the X-ray must be the largest calibre of bullet that the bullet in the body can possibly be. For example, if the image is the same size as a 0.25" calibre bullet, then the bullet in the body must be of a smaller calibre than 0.25".

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  • Marcel
    Does magnification effect ballistics?
    8 years ago
  • Arcangelo
    What is missile calibre?
    8 years ago

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