These law enforcement sources that the media use are either not very knowledgeable or misquoted. I know most reports say an AK-47 type weapon was used but I still believe it was an AR15. More sheeple know what an AK-47 is. Read this quote and notice what caliber is specified.
A federal law enforcement source tells CNN's Susan Candiotti that the suspect had the following weapons:  A 12-gauge shotgun with a legal capacity of up to three shells. Shotguns like this can be modified to increase their capacity, the source said.  An "AK-47 style" assault rifle normally equipped with a magazine capable of firing up to 30 rounds of .223-caliber ammunition. It's not known whether it was an automatic or semi-automatic model.  Two handguns.
What type of rifle does that describe?
For anyone wondering this theater is 13 miles from Columbine H.S.