Step #1
Draw rectangles.
Step #2
Draw shape as shown.
Step #3
Draw barrel as shown.
Step #4
Draw chamber.
Step #5
Draw bolt as shown.
Step #6
Draw outline for body.
Step #7
Draw hands.
Step #8
Draw shape as shown.
Step #9
Enhance drawing.
Step #10
Enhance drawing.
Step #11
Enhance drawing.
Step #12
Make necessary improvements to finish.