[ltc8k6]

“Lanza changed magazines frequently as he fired his way through the first-grade classrooms of Lauren Rousseau and Victoria Soto, sometimes shooting as few as 15 shots from a 30-round magazine, sources said.

More than a week after the shooting, investigators were still finding bullets under doors and in carpets and walls in the school as they tried to match the casings to the magazines.”

http://www.courant.com/news/connecticut/newtown-sandy-hook-school-shooting/hc-sandyhook-lanza-earplugs-20130106,0,2370630.story

[loboinok]

"All 26 of Lanza's victims were shot with the .223-caliber semi-automatic rifle," said Vance

"More than a week after the shooting, investigators were still finding bullets under doors and in carpets and walls in the school as they tried to match the casings to the magazines.”

What is difficult about matching casings to magazines if they were all shot with the same rifle?