Here's my effort and the result.
1. Crop the bitmap to include just the rifle and the scales 7" x 25"
2. Manually trace the rifle from the bitmap.
3. Draw 2 master guide lines 25" long 7" apart on a new layer.
4. On another layer draw 2 corresponding lines on the bitmap following the lines on it.
4. Copy the rifle tracing and drawn bitmap guide lines onto another layer. Make this layer active. Turn off all of the other layers except the one with the master grid lines.
5.. Select the rifle tracing and the grid lines that were drawn on the bitmap. Distort these vectors so the lines on the bitmap overlay the master guide lines.You can use distortion tool and/or the handles that appear when you double clock on the selected lines.
Note: If you use the distortion tool, all of the vectors selected end up on the active layer and are no longer regular curves. You have to double click on the result and select "Convert to curves" before you can make any more changes.
Good judgement comes from experience.
Experience comes from bad judgement.