Complex sentence: To facilitate cleaning, the ejector was built into the magazine rather than the body of the gun, allowing the barrel to be rapidly removed by pulling up a spring-loaded plunger in front of the magazine housing.
Split into simpler sentences: To facilitate cleaning, the ejector is built into the magazine, rather than the body of the gun. This allows the barrel to be removed rapidly, by pulling up a spring-loaded plunger in front of the magazine housing.