Complex sentence: The 305-millimeter guns were bored out to and their turrets were modified to use electric power, a fixed loading angle of +12 degrees, and the guns could now elevate to +27 degrees.
Split into simpler sentences: The 305-millimeter guns were bored out to and their turrets were modified to use electric power. They had a fixed loading angle of +12 degrees, and the guns could now elevate to +27 degrees.