It depends on which gun. Different guns assemble in different ways.
It depends on what type of gun it is. You should check the owners manual.
hjg
How do you assemble a jc higgins 103.229 22 rifle
Marvel's Avengers Assemble - 2013 1-22 was released on: USA: 2014
Easy to Assemble - 2008 was released on: USA: 22 September 2008 USA: 22 September 2008
well you get the instuctions out and wallah you guns assembled
in front ps you are stupid
look for internal pictures on nerfhaven.com and match your gun with the picture.
Avengers Assemble - 2010 Hawkeye's Webcam was released on: USA: 22 October 2010
Try Mid West Gun Works or Browning for a manual
Best left to a gunsmith