The judge heard testimony Wednesday from a state crime scientist who said he matched bullets and shell casings found at the theatre to three weapons, apparently the ones officers seized at the scene.
The defence wants firearms testimony barred from the trial.
James Holmes pleaded not guilty by reason of insanity to charges of killing 12 people and injuring 70 in the 2012 attack. Prosecutors are seeking the death penalty.
Defence lawyers have acknowledged Holmes was the shooter but continue to challenge any evidence prosecutors present.
Holmes' attorneys say he was in the grip of a psychotic episode at the time of the shootings.