thoseinperil:

The actual weapons used by Eric Harris and Dylan Klebold on display at the Jefferson County Fairgrounds, February 26, 2004. The majority of the items displayed include the pump action shotguns, pipe bombs, and multiple knives each carried during the attack on Columbine on April 20, 1999.  

In the last image you can see the fake guns used during ‘Radioactive Clothing’. Other photos contain objects they possessed but may not have used during the attack.