Papercraft The Flintlock Rubber Band Gun 

From Made-this, thisPaper Toy The Mexican Revolver 

Indiana Jones  Webley Mk VI Revolver

M14 Rifle 

Sniper Rifle Cheytac M200 Intervention 

Automatic AA12  Shotgun also called Auto Assault 12

Revolvrr (Revolver):

A funny papercraft "Revolvrr", prepare to shoot... paper!

Star Wars DL44 Killer Greedo