I found a tutorial on how to draw a rifle on howtodrawforkids.com. Here are the steps:

1. Outline the barrel of the rifle in the form of a long and flat rectangle.
2. Outline the forearm and stock of the rifle.
3. Sketch out such details as a sight, clamps, trigger, trigger guard, and the ejection port.
4. Draw the buttstock and magazine.
5. Add details such as screws and bolts.

You can also find tutorials on how to draw other types of rifles such as Winchester rifles, AK-47 rifles, and assault rifles on drawingtutorials101.com and stepbystepforkids.com.