Lab 4 - Firearms
PRE-LAB QUESTIONS
1. What are the winding grooves which help a bullet maintain a stable trajectory
called?
-
The winding grooves are rifling. Rifling helps to maintain a stable
trajectory.
2. Would you expect to find more gunshot residue around an entrance or exit
hole? Explain your reasoning.
-
You would find more gunshot residue around the entrance hole because
this is the first point of contact and encounters the surface. As the bullet
travels, it begins to lose gunshot residue, so there would be less at the exit
hole.
3. Would a hand gun or shot gun be more difficult to trace and determine class
characteristics? Explain your answer.
-
Shot guns would be more difficult because there is no rifling or markings
that can be consistent enough to match between two guns.
Exercise 1
Post-Lab Questions
Bullet Hole Minor Axis (mm)
8 mm
Bullet Hole Major Axis (mm)
9.3 mm
Angle of Bullet Impact
59.34 degrees
Approximate Shoulder Height
(inches)
45.35 inches
1. Record your calculations from Step 2 here.
-
Sin^-1(8/9.3) = 59.34 degrees
2. Draw the diagram from Step 6 here.
3. Record your calculations from Step 7 here.
